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I 


AUTOGENOUS 
WELDING  AND  CUTTING 


McGraw-Hill  BookGompany 

Purffis/iers  ofBoo£§/br 

Electrical  World         TheEn^neerin^andMinin^Joui-iial 
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Metallurgical  and  Chemical  Engineering  Power 


AUTOGENOUS 
WELDING  AND  CUTTING 


BY 

THEODORE  KAUTNY,   ING, 

NURNBERG 

TRANSLATED  BY  THE  AUTHOR 
AND 

JAMES   F.   WHITEFORD 


MEMBER   AM.    SOC.   MECH.    ENGRS. 


FIRST  EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 

239  WEST  39TH  STREET,  NEW  YORK 

6  BOUVERIE  STREET,  LONDON,  E.G. 
1915 


<v 

*? 


COPYRIGHT,  1915,  BY  THE 
MCGRAW-HILL  BOOK  COMPANY,  INC. 


AUTHOR'S  PREFACE 

THE  literature  of  autogenous  welding  technique  has 
been  enriched  lately  in  many  valuable  ways,  and  there 
exist  a  large  number  of  works  which  cover  this  field. 

Autogenous  welding  is  a  process  intended  for  general 
introduction  both  in  small  workshops  and  in  large 
factories.  The  range  of  welding  technique  is  so  wide 
that  a  thorough  study  of  the  process  requires  extensive 
research  which  makes  great  demands  on  the  time  of 
the  reader. 

A  pocket  book  of  brief  compass  will  be  welcome  to 
the  works  engineer,  to  the  works  foreman,  and  to 
the  practical  autogenous  welder;  in  which  the  most  im- 
portant elements  of  the  process  are  placed  together  in 
an  easily  available  manner,  and  which  shall  be  a  faithful 
companion  and  a  reliable  adviser  in  connection  with  the 
various  questions  arising  in  practice. 

The  object  of  the  present  work  is  to  meet  these 
requirements  and  I  pass  it  on  to  the  general  public  in 
the  hope  that  it  will  be  favorably  received  and  fulfil 
its  task. 

THEO.  KAUTNY 
NURNBERG,  April,  1914. 


331179 


COLLABORATOR'S  PREFACE 

THE  rapid  extension  of  the  application  of  autogenous 
welding  by  means  of  the  oxyacetylene  flame,  which  fol- 
lowed closely  upon  the  perfecting  of  apparatus  for  the 
commercial  production  of  oxygen  and  acetylene,  has  by 
no  means  exhausted  the  field  for  this  process  of  metal 
working. 

New  developments  are  being  continually  recorded 
and  it  would  be  exceedingly  difficult  to  establish  any 
definite  limits  in  the  application  of  the  process. 

As  the  development  of  the  art  of  autogenous  welding 
is  being  advanced  in  other  countries  simultaneously 
with  those  of  English  speaking  people  it  is  important 
for  provision  to  be  made  so  that  students  and  others 
interested  in  the  subject  may  become  familiar  with  the 
methods  and  practices  in  use  elsewhere. 

In  Germany,  the  industrial  applications  of  the  proc- 
ess are  of  such  importance  and  the  value  of  detailed 
knowledge  is  so  fully  appreciated,  that  autogenous  weld- 
ing schools  are  now  conducted  in  conjunction  with  the 
Technical  High  Schools  in  various  centers. 

As  the  author  has  been  closely  associated  with  the 
establishment  of  these  schools  the  text  in  the  following 
pages  is  of  particular  importance. 

Effort  has  been  made  to  avoid  the  use  of  such  tech- 
nical terms  as  may  confuse  the  individual  welder, 
and  to  give  such  information  and  instruction  as  will 
enable  him  to  more  thoroughly  understand  and  appre- 


viii  COLLABORATOR'S  PREFACE 

ciate  the  art  which  engages  his  attention,  since  the 
success  of  the  application  of  the  process  depends  so 
largely  upon  the  correct  knowledge  and  skill  of  the 
individual. 

JAMES  F.  WHITEFORD 
LONDON,  July,  1914. 


CONTENTS 


PAGE 

AUTHOR'S  PREFACE v 

COLLABORATOR'S  PREFACE vii 


CHAPTER  I 

AUTOGENOUS  WELDING  FLAMES 

Welding-  applications 1 

Combustible  gases 2 

Hydrogen 2 

Blau  gas 4 

Illuminating  gas 4 

Benzol  vapors 4 

Acetylene 5 

CHAPTER  II 

ACETYLENE  MANUFACTURE  AND  APPARATUS 

Calcium  carbide 7 

Properties  of  calcium  carbide 7 

Commercial  sizes  of  grains 7 

Method  of  storage 8 

Classification  of  generators 8 

Carbide  to  water  generators 10 

Overheated  acetylene  and  its  effect  on  welds 11 

Gasifying  dust  carbide 14 

Water  to  carbide  generators : 16 

Automatic  water  displacement  generators 17 

Use  of  "Beagid" 18 

Dissolved  acetylene 19 

Purification  of  acetylene 19 

Chemical  purifiers 20 

Mechanical  purifiers 21 


x  CONTENTS 

CHAPTER  III 
OXYGEN  MANUFACTURE  AND  APPARATUS 

PAGE 

Purchase  of  oxygen  in  steel  bottles 23 

Method  and  apparatus  for  testing  oxygen 24 

Liquid  air  process  of  manufacture  of  oxygen 24 

Electrolytic  process  of  manufacture  of  oxygen 25 

Chemical  process  of  manufacture  of  oxygen 26 

Operation  of  oxygen  bottles 26 

Pressure  reducing  valves  for  oxygen  bottles 28 

CHAPTER  IV 

GAS  MAINS  AND  FITTINGS 

Piping  of  acetylene  in  a  welding  shop 31 

Pressure  of  acetylene  in  the  welding  shop 31 

Danger  of  back  firing 31 

Safety  devices 32 

Selection  and  operation  of  connection  hose 33 

'CHAPTER  v 

AUTOGENOUS  WELDING  BURNERS 

Equal  pressure  burners 35 

Injector  burners 36 

Adjustable  burners 36 

Burners  with  interchangeable  tips 37 

Flame  adjustment 37 

Detail  of  burner  construction 39 

Gas  consumption  of  burners 42 

CHAPTER  VI 
AUTOGENOUS  CUTTING  BURNERS 

Classification  of  cutting  burners 44 

Principle  of  cutting  with  oxygen 44 

Guiding  devices  for  cutting  burners 45 

Industrial  applications  of  autogenous  cutting 47 

Data  on  cutting  with  oxygen  and  acetylene 48 

Data  on  cutting  with  oxygen  and  hydrogen 48 

Effect  of  variation  in  the  purity  of  oxygen 49 


CONTENTS  xi 

CHAPTER  VII 

AUTOGENOUS  WELDING  OF  IRON 

PAGE 

Properties  of  iron 50 

Carbon  in  molten  iron 50 

Influence  of  an  excessive  quantity  of  carbon 54 

Pearlite  or  cementite 56 

Welding  of  cast  iron 58 

Special  filling  material  required  for  cast  iron  welds 59 

Preparation  and  execution  of  the  weld 60 

Necessity  for  use  of  flux  in  welding  cast  iron 60 

Welding  of  cast  steel 61 

Welding  of  hard  steel 61 

Welding  of  wrought  iron 62 

Conditions  producing  martinsite 62 

CHAPTER  VIII 

REPAIRS  OF  GREY  CAST  IRON 

Formation  of  white  iron 63 

Presence  of  tensions  in  castings 63 

Benefits  derived  from  preheating 64 

Expansion  of  cast  iron  during  welding  operation 64 

Method  of  repairing  large  or  complex  castings 66 


CHAPTER   IX 
WELDING  OF  SHEET  IRON 

Welding  methods  vary  for  sheets  of  different  thickness 68 

Flanging  of  sheets  for  welding  operation 69 

Method  of  welding  very  thin  sheets 70 

Position  of  the  welding  burner 70 

Failures  of  welds 71 

Existence  of  oxides  and  their  influence  on  welds 72 

Magnetic  properties  of  iron 74 

Value  of  reheating  the  welded  portion 75 

Puddling  process  to  supplement  the  use  of  the  welding  burner.  76 

Simultaneous  use  of  two  welding  flames 77 

Vertical  and  overhead  welding 78 


xii  CONTENTS 

CHAPTER  X 

MANUFACTURE  AND  REPAIRS  OF  BOILERS 

PAGE 

Properties  of  mild  steel  boiler  sheets 80 

Causes  of  failures  of  boiler  sheets 80 

Influence  of  autogenous  welding  on  boiler  construction 81 

Method  of  welding  up  cracks 82 

Application  of  patches 83 

Employment  of  the  puddling  process 84 

Repairs  of  corroded  tubes 85 

CHAPTER  XI 

MANUFACTURE  OF  CYLINDRICAL  VESSELS 

Devices  for  use  in  welding  cylindrical  sections 86 

Welding  of  horizontal  seams 87 

Welding  of  circumferential  seams 88 

Method  of  executing  welds  on  heavy  sheets 89 

Joining  sheets  of  different  cross  section 91 

Application  of  joint  rings 91 

Problems  involved  in  manufacture  of  closed  cylindrical  vessels  93 

Application  of  heads 94 

Method  employed  for  annular  welding 95 

Method  for  applying  intermediate  heads 98 

CHAPTER  XII 

MANUFACTURE  OF  RECTANGULAR  VESSELS  AND 
MISCELLANEOUS  ARTICLES 

Problems  involved  in  manufacture  of  rectangular  vessels 99 

Position  of  welding  burner 99 

Location  of  the  welding  seams 99 

Manufacture  of  safes 100 

Superheaters  and  radiators 100 

Automobile  and  aeronautical  motors 101 

Double  shell  vessels 103 

Open  sheet  metal  vessels 104 

Cooking  utensils 105 

Structural  iron  work 105 


CONTENTS  xiii 


CHAPTER  XIII 

MANUFACTURE  AND  INSTALLATION  OF  LARGE 
PIPES  AND  CONDUITS 

PAGE 

Application  of  tee  connections 107 

Manufacture  of  large  elbows 108 

Method  of  applying  connection  flanges 109 

Use  of  welded  pipe  in  ship  building 110 

Method  of  overcoming  expansions  difficulties Ill 

CHAPTER  XIV 

MANUFACTURE  AND  INSTALLATION  OF  GAS 
AND  WATER  PIPE 

History  of  development  in  pipe  manufacture 112 

Difficulties  encountered  in  the  earlier  methods 113 

Adoption  of  the  autogenous  welding  process 113 

Difficulties  experienced  in  welding  pipe 114 

Description  of  autogenous  pipe-welding  machines 115 

Benefit  derived  from  preheating  116 

Securing  reliability  of  flame  for  welding 117 

Installation  of  pipes  by  welding 118 

Advantages  offered  by  autogenous  welding  method 119 

Education  of  the  welders 119 

CHAPTER  XV 
CONSTRUCTION  OF  PIPE-SHAPED  APPARATUS 

Heat  exchange  apparatus 121 

Ammonia  machines 121 

Bicycle  tubing 123 

Aeroplane  frames 124 

Metal  furniture 125 

Tapered  tubing 126 

CHAPTER  XVI 
WELDING  OF  COPPER 

Properties  of  copper  and  their  influence  on  welding 127 

Nature  and  use  of  welding  powders 128 

Adjustment  and  operation  of  the  welding  flame 129 


xiv  CONTENTS 

PAC 

Description  of  various  methods  of  welding  copper 1< 

Execution  of  the  puddling  process. 1< 

CHAPTER  XVII 

WELDING  OF  ALUMINIUM 

Properties  of  aluminium  which  influence  autogenous  welding. 

Existence  and  influence  of  the  oxide  in  welding 

Methods  of  destroying  the  oxide 

Nature  and  use  of  welding  powders 

Schoop  patent  process  of  welding  aluminium 

Welding  of  sheet  aluminium 1 

CHAPTER  XVIII 
WELDING  OF  NICKEL  AND  OTHER  METALS 

Properties  of  nickel  which  influence  autogenous  welding 1 

Use  of  a  heated  anvil 1 

Hammering  process 1 

Autogenous  repairs  of  nickel 

General  rules  for  welding  nickel 

Autogenous  welding  of  silver 

Autogenous  welding  of  gold • 

Autogenous  welding  of  lead 

Welding  together  of  different  metals . .'. 

CHAPTER  XIX 
CONCLUSION 

Trend  of  development  m  autogenous  welding 1' 

Influence  of  technical  refinements 1' 

Importance  and  possibilities  of  the  puddling  process 1- 

INDEX.  .  1- 


AUTOGENOUS  WELDING  AND 
CUTTING 

CHAPTER   I 
AUTOGENOUS    WELDING    FLAMES 

AUTOGENOUS  welding  is  a  process  by  which,  through 
the  use  of  a  hot  blow  pipe  flame,  the  edges  of  metal 
parts,  placed  against  each  other,  are  heated  to  their 
melting  point  so  they  will  flow  into  one  another.  After 
the  welding  and  cooling  the  parts  form  one  body  of 
almost  the  same  physical  properties. 

The  applications  of  the  process  in  industry  are  both 
numerous  and  varied  and  its  already  wide  field  of  prac- 
tical uses  is  being  rapidly  extended.  It  is  used  to 
replace  the  seaming,  rivetting  and  hard  soldering  of 
metal  sheets  and  for  the  installation  of  permanent 
plumbing  fixtures  and  gas  and  water  pipe. 

In  the  manufacture,  from  strips  of  sheet  metal,  of 
piping  and  tubing  of  various  kinds  and  dimensions, 
which  are  used  for  gas,  water  and  steam  conduits  and 
also  for  the  construction  of  different  parts  of  bicycles, 
automobiles  and  aeroplanes. 

The  process  is  also  used  in  the  building  trades,  for 
making  numerous  parts  out  of  rolled  metal,  as  metal 
door  and  window  frames,  for  the  reinforcing  of  concrete, 
and  for  decorative  metal  work. 

In  the  construction  of  internal  combustion  motors, 
to  make  various  fittings  and  connections  as  well  as 
for  manufacturing  the  jacket  of  water-cooled  cylinders. 

In  the  shipbuilding  industry,  for  the  construction 
and  erection  of  pipes,  as  well  as  for  boiler  repairs. 

1 


2  AUTOGENOUS  WELDING  AND  CUTTING 

In  the  machine  shop  and  foundry,  to  repair  worn 
and  defective  castings  of  all  kinds. 

It  is  also  extensively  used  to  replace  hard  soldering 
in  the  finer  metals  and  to  manufacture  metal  furniture 
and  sundry  household  articles  of  copper,  aluminium 
and  nickel. 

Combustible  Gases.  —  For  autogenous  welding  vari- 
ous combustible  gases  are  used  in  conjunction  with 
oxygen,  to  secure  a  flame  of  sufficient  temperature  to 
fuse  metallic  parts. 

These  gases  are  hydrogen,  Blau  or  liquid  gas,  illumi- 
nating gas,  benzine  or  benzol  vapors,  and  acetylene. 

Hydrogen.  —  Hydrogen  gas  is  a  chemical  element 
which  exists  in  nature,  in  great  quantities,  in  various 
chemical  combinations.  Of  these,  the  most  common 
is  water,  its  combination  with  oxygen  (H2O),  and  as  a 
consequence  water  is  used  as  a  basis  for  the  manufac- 
ture of  hydrogen. 

Inasmuch  as  the  separation  of  water  into  its  ele- 
ments means  the  destruction  of  a  chemical  combina- 
tion, considerable  mechanical  power  is  required. 

Just  as  the  separation  of  the  chemical  parts  of  water 
requires  a  considerable  amount  of  power,  so  the  com- 
bination of  these  elements  —  which  takes  place  in  the 
burning  of  such  mixture  known  as  oxy-hydrogen  gas 
—  develops  a  considerable  amount  of  heat.  Therefore 
the  flame  caused  by  the  burning  of  oxy-hydrogen  gas 
can  be  used  for  autogenous  welding. 

The  burning  of  a  molecular  equivalent  mixture  of 
oxygen  and  hydrogen  results  in  the  forming  of  water. 
Water,  however,  when  superheated  at  a  high  tempera- 
ture, as  under  the  influence  of  a  blow  pipe  flame,  dis- 
sociates again  into  its  elements. 

In  using  this  flame  for  autogenous  welding  the  danger 
exists  that,  during  the  formation  of  oxygen  and  hydro- 


AUTOGENOUS  WELDING  FLAMES  3 

gen  within  the  flame,  the  oxygen  will  unite  with  the 
metal,  i.e.  the  metal  will  burn,  or,  what  corresponds  to 
a  lower  degree  of  burning,  the  metal  will  become  over- 
heated. 

The  temperature  of  a  hydrogen-oxygen  flame  can 
never  go  higher  than  the  dissociation  temperature 
of  water  which  is  estimated  at  2000°  C.  (3632°  F.). 

To  prevent  the  burning  or  overheating  of  metals 
in  welding  with  hydrogen-oxygen,  it  becomes  necessary 
to  use  a  supercharge  of  hydrogen;  in  order  that  the 
oxygen  liberated  within  the  flame  combines  again 
with  the  free  hydrogen,  and  thus  making  it  harmless 
for  the  iron.  This  practice,  however,  increases  the  size 
and  decreases  the  temperature,  of  the  flame. 

Hydrogen  is  handled  commercially  in  steel  cylinders 
under  a  pressure  of  150  atmospheres. 

A  hydrogen-oxygen  welding  outfit  consists  of  2 
steel  cylinders;  one  containing  compressed  hydrogen 
and  the  other  compressed  oxygen.  Each  cylinder  is 
supplied  with  a  pressure  reducing  valve  connected  with 
the  welding  burner  by  means  of  flexible  tubes. 

In  the  operation  of  a  hydrogen-oxygen  welding 
apparatus,  if  the  burner  is  brought  too  near  to  the 
metal,  a  black  spot  can  be  observed  in  the  middle  of 
the  glowing  metal.  This  is  due  to  the  metal  being 
cooled  by  the  unburnt  gas  mixture  and  such  a  condi- 
tion must  be  avoided. 

For  the  welding  of  thin  metal  sheets,  the  use  of  oxy- 
hydrogen  is  practical,  although  the  quality  of  the 
welding  seam  decreases  as  the  thickness  of  the  metal 
increases. 

Oxy-hydrogen  welding  was  the  first  autogenous  weld- 
ing system  employed  and  was  used  extensively  until 
the  more  advantageous  system  of  welding  with  acety- 
lene was  introduced,  which  latter  system  has  now 


4  AUTOGENOUS  WELDING  AND  CUTTING 

almost  entirely  replaced  the  welding  with  the  oxy- 
hydrogen  flame. 

Blau  or  Liquid  Gas.  —  Blau  1  or  liquid  gas  is  manu- 
factured by  vaporizing  liquid  hydrocarbons  in  closed 
retorts  and  superheating  the  vapors.  This  is  not  a 
chemical  combination  but  a  mechanical  mixture  of 
various  gases  and  vapors. 

When  this  gas  is  used  for  welding,  the  free  hydrogen 
contained  in  the  products  of  combustion  is  absorbed 
by  the  iron.  In  working  heavier  sheets,  necessitating 
a  prolonged  use  of  the  flame,  an  extensive  absorption  of 
the  hydrogen  by  the  metal  occurs.  As  the  metal 
solidifies,  the  absorbed  hydrogen  is  expelled  producing 
a  porous  welding  seam. 

For  the  welding  of  certain  metals,  as  aluminium,  and 
for  welding  thin  metal  sheets,  the  employment  of 
Blau  gas  is  practical,  but  such  operation  is  very  ex- 
pensive on  account  of  the  high  cost  of  compressing  and 
transporting  the  gas. 

Illuminating  Gas.  —  Illuminating  gas  (coal  gas  and 
water  gas)  can  only  be  used  for  welding  very  thin 
metal  sheets,  owing  to  the  low  temperature  of  the 
flame.  On  account  of  the  great  loss  of  heat  caused  by 
the  absorbing  and  conductive  qualities  of  the  metal, 
it  is  impossible,  with  a  flame  of  low  temperature,  to 
heat  thick  metal  sheets  locally  to  the  melting  point. 

Benzin^  or  Benzol  Vapors.  —  In  autogenous  welding, 
the  vapors  of  liquid  hydrocarbons  have  the  same  prop- 
erties as  Blau  or  liquid  gas.  The  temperature  of  a 
Benzol  welding  flame  at  about  2700°  C.  (5000°  F.)  is 
higher  than  the  illuminating  gas  welding  flame,  but 
is  considerably  lower  than  that  of  the  oxygen-acety- 
lene flame. 

1  This  gas  derives  its  name  from  that  of  the  inventor,  a  chemist, 
Blau  of  Augsburg,  Germany. 


AUTOGENOUS  WELDING  FLAMES  5 

Numerous  tests  have  proved  that  Benzol  welding  is 
less  advantageous  from  an  economical  and  qualita- 
tive standpoint  than  the  oxy-acetylene  or  the  oxy- 
hydrogen  welding,  but  the  process  may  be  used  to 
advantage  for  many  purposes,  especially  for  the  weld- 
ing of  light  pieces.  Further,  the  apparatus  used  for 
such  welding  is  capable  of  being  moved  easily  from 
place  to  place. 

Acetylene.  —  The  use  of  acetylene  in  autogenous 
welding  has  rapidly  extended  since  its  first  introduc- 
tion. This  is  due  to  the  peculiar  conditions  resulting 
from  the  burning  of  acetylene  in  a  stream  of  oxygen. 

Acetylene  is  a  chemical  combination  of  carbon  and 
hydrogen  (C2H2)  and  the  burning,  i.e.  its  combina- 
tion with  oxygen,  takes  place  in  two  phases,  with  a 
well  defined  zone  formed  of  the  first  phase. 

This  zone  consists  of  the  products  of  combustion  of 
the  first  phase,  i.e.  carbon  monoxyde  and  hydrogen, 
which  products  combine  with  the  oxygen  of  the  air, 
in  an  exterior  envelope  of  the  flame,  to  the  final  prod- 
ucts of  combustion,  i.e.  carbonic  acid  and  water. 

In  autogenous  welding  this  zone  within  the  flame 
is  active  while  the  outer  envelope  serves  to  protect 
the  metal  against  oxidation.  The  formula  of  the  chem- 
ical changes  is  as  follows :  — 

C2H2  +  2O  =  2CO  +  H2  and 
2CO  +  H2  +  3O  =  2CO2  +  H20 

Acetylene  consists  of  a  chemical  combination  of 
2  atoms  of  carbon  and  2  atoms  of  hydrogen  (C2H2). 
Inasmuch  as  the  carbon  is  two-atomic,  the  acetylene 
forms  a  non-saturated  compound  and  there  exists 
therefore,  in  the  acetylene  molecule,  a  certain  interior 
tension. 

This    causes    the    gas    to    form    other    combinations 


6  AUTOGENOUS  WELDING  AND  CUTTING 

belonging  to  the  acetylene  group  at  the  comparatively 
low  temperature  of  480°  C.  (896°  F.)  .which  phenomena 
is  called  Polymerisation.  Such  higher  combinations 
of  the  acetylene  are  Benzin,  Benzol,  Styrolin,  Naphtha- 
lin,  etc. 

Benzol,  like  the  balance  of  these  combinations,  has 
physical  properties  different  from  acetylene  and  this 
is  the  reason  why  Benzol  vapors  used  in  place  of 
acetylene  do  not  give  the  expected  results  in  autogenous 
welding. 

Furthermore,  such  polymeres  of  acetylene  are  liable 
to  condense  part  of  their  carbon  in  the  form  of  tar- 
products  under  circumstances  existing  in  an  acetylene 
generator. 


CHAPTER   II 
ACETYLENE   MANUFACTURE   AND    APPARATUS 

THE  basis  for  manufacturing  acetylene  is  calcium 
carbide,  which  is  produced  by  melting  together  lime  and 
coke  in  an  electric  furnace. 

Calcium  Carbide.  —  Calcium  carbide  is  a  crystalline 
substance  usually  of  grey  color  and  is  immune  against 


FIG.  1.  —  Granulated  carbide 
grains  Nos.  1  to  3.     (£  size.) 


FIG.  2.  —  Granulated  carbide  grains 
Nos.  4  to  7.     (i  size.) 


the  action  of  most  acids.  It  combines  in  all  its  forms 
with  water  forming  hydrate  of  lime  and  acetylene  gas 
and  must  therefore  be  protected  against  all  dampness. 

For  commercial  use  it  is  packed  in  tin  drums  of  50 
or  100  Ibs.  each  and 
can  be  purchased 
in  the  following 
granulations : — f", 
i",  I",  J",  1 


2"  (Figs.  1,  2,  3). 

All  sizes  UD  to  -"        -^IG>  ^' —  Ganulated  carbide  grains  Nos. 

8  to  15.     (i  size.) 

are  known  as  gran- 
ulated carbide;    larger  sizes  as  lump  carbide. 
The  various  apparatus  for  the  manufacture  of  acety- 

7 


8 


AUTOGENOUS  WELDING  AND  CUTTING 


lene  are  constructed  for  certain  sizes  of  carbide  grains 
and  the  correct  size  must  be  used,  as  otherwise  the 
operation  of  the  machine  will  be  irregular  and  under 
certain  conditions  too  much  gas  will  be  developed  which 
may  become  dangerous. 

Carbide  packed  in  metal  drums  may  be  safely  kept 
in  the  same  room  as  the  generator  but 
the  carbide  must  be  kept  absolutely 
dry  (Fig.  4).  These  drums  are  often 
damaged  in  handling,  and  if  water  in 
any  form  reaches  the  carbide,  acety- 
lene is  generated  and  great  danger 
of  explosion  arises.  It  is  therefore 
advisable  to  store  carbide  cans  on 
wooden  supports  (Fig.  5). 

Carbide  drums  have  either  a  screw 
cover  or  the  opening  on  top  is  closed 
by  a  sheet  metal  plate  soldered  on.  In 

FIG.    4.  —  Cross   sec-        , 

tion  of  carbide  drum    the  latter  case,  care  must  be  exercised 

fitted   with  socket    jn  the  opening  of  the  drums,  as  a  steel 

chisel  used  for  such  operation   may 

cause  a  spark  by  contact  with  the  drum  which  would 

ignite  any  acetylene  that  might  exist  within. 

Generators.  —  For  regular  welding  work  in  factories, 
stationary  acetylene  genera- 
tors should  be  given  the  pref- 
erence and  these  should  be 
made  according  to  the  ex- 
isting local  regulations. 

Portable  outfits  may  be 
used  to  advantage  in  the  in- 
terior of  the  factories  but  sta- 


FIG.  5.  —  Carbide  storage  drum 
supported  by  wooden  blocks 
for  protection  against  water. 


tionary  plants  have  been  found  to  be  more  economical 
as  the  production  of  the  gas  is  more  easily  regulated 
and  overheating  can  be  more  easily  avoided. 


ACETYLENE  MANUFACTURE  AND  APPARATUS 


9 


During  the  transformation  of  the  water  and  carbide, 
a  considerable  amount  of  heat  is  liberated  which  has 
been  calculated  at  220  British  Thermal  units  for  each 
pound  of  carbide  gasified. 

With  4|  pounds  of  water  and  1  pound  of  carbide 
the  temperature  of  the  water  will  be  raised  to  the 
boiling  point  and  steam  will 
be  formed  which  will  reduce 
the  active  amount  of  water 
in  the  generator.  It  follows 
therefore  that  the  quantity  of 
water  in  the  generator  must 
be  greater  than  4J  pounds  for 
each  pound  of  carbide  and  this 
must  be  given  consideration 
in  designing  generators. 

Acetylene  generators  may 
be  divided  into  two  classes, 
viz:  — 

1.  Generators  in  which 
small  quantities  of  carbide  are 
introduced,  by  hand   or  me- 
chanical  arrangement,  into  a 

/-re         c    n     FIG-    6.  —  Cross  section  of  por- 
SUrpluS  Ot   water.      (..blgS.  b,  7,        table  automatic   "carbide   to 

8,  9,  10,  11,  12.) 

2.  Generators  in  which  a 
quantity  of  water  flows  into  a 
chamber  partially  filled   with 
carbide,  the  quantity  of  water 
being  regulated  by  mechanical 
action.     (Figs.  13,  14,  15.) 

Generators  of  both  types  are 
in  use  which  give  satisfactory  results,  but  there  are  also 
generators  of  each  type  that  not  only  result  in  poor 
welding  but  which  are  dangerous  to  operate. 


water  "  acetylene  generator. 

A.  Gas  chamber. 

B.  Water  Seal. 

C.  Gas  delivery  pipe. 

D.  Carbide  holder. 

E-F.    Delivery  mechanism. 

G-H.    Delivery  chute. 

K.    Purifier. 

P-Q.    Delivery  regulator. 

W.   Cleaning  pipe. 

Z.    Gas  valve. 


10 


AUTOGENOUS  WELDING  AND  CUTTING 


Carbide  to  Water  Generators.  —  The  generators  of 
the  first  group,  carbide  to  water,  should  be  so  con- 
structed that  for  each  weight  unit  of  carbide  10  weight 
units  of  water  are  available  and  that  the  latent  heat 
in  the  carbide  is  distributed  over  the  entire  quantity  of 

water  so  that  a  temperature 
of  45°  C.  (113°  F.)  is  not 
exceeded. 

In  order  to  distribute  the 
heat  over  the  entire  quan- 
tity of  water,  it  is  necessary 
to  provide  a  grate  on  which 
the  carbide  rests  during  the 
gasification  process.  In  this 
manner  the  heat  is  absorbed 
by  the  surrounding  water, 
which  reduces  its  specific 
gravity  and  causes  it  to  rise 
to  the  surface,  while  the 
cooler  water  along  the  walls 
of  the  generator  flows  down- 
wards. 

It  is  of  advantage  to  use 
in  cylindrical  generators  a 
grate  fastened  on  a  shaft  which  can  be  operated  from 
without,  in  order  to  loosen  the  residue  on  the  bottom 
of  the  generator.  It  is  of  the  greatest  importance  for 
the  welder  that  the  apparatus  is  kept  scrupulously 
clean  and  that  a  sufficient  quantity  of  clean  water  is 
provided. 

When  a  quantity  of  mud  or  sludge  has  accumulated 
in  the  generator,  the  fresh  carbide  introduced  will 
become  imbedded  in  the  sludge  and  will  not  reach 
the  grate.  The  circulation  of  the  water  will  thus  be 
impeded  so  that  great  heat  will  develop  locally  and 


FIG.  7.  —  Delivery  device  of  a  high 
pressure  "carbide  to  water" 
acetylene  generator. 


ACETYLENE  MANUFACTURE  AND  APPARATUS        11 

with  the  introduction  of  air  into  the  generator  —  as 
happens  when  the  apparatus  is  refilled  —  explosions 
are  liable  to  occur. 

In  such  cases  the  gas  generated  becomes  overheated 
causing  the  phenomenon  of  polymerisation  and  for 
our  purpose  such  gas  will  be  designated  as  overheated 
acetylene. 

Overheated  Acetylene.  —  Overheated  acetylene  there- 
fore is  a  gas  which  by  means  of  the  heat  resulting  from 
the  decomposition  of  the  carbide,  is  partially  trans- 
formed into  the  vapors  of  liquid  hydrocarbons.  These 
vapors  condense  in  this  reacting  mass,  their  carbon 
forming  tar  products.  The  overheating  of  the  acety- 
lene in  the  generator  is  indicated  by  a  local  yellow 
or  brown  discoloration  of  the  lime  sludge  caused  by  the 
tar  products. 

The  accumulation  of  sludge  is  a  very  important 
factor  in  the  operation  of  all  apparatus  into  which 
carbide  is  dropped.  Even  in  such  generators  where 
the  carbide  is  introduced  within  perforated  drums,  an 
accumulation  of  lime-sludge  must  be  expected. 

In  many  acetylene  generators  the  carbide  is  intro- 
duced in  perforated  metal  boxes,  which  are  placed 
within  other  metal  holders.  In  such  apparatus  the 
greater  part  of  the  lime-sludge  will  remain  within  these 
metal  holders,  in  which  case  cleaning  the  generator 
at  weekly,  or  even  longer  intervals,  is  satisfactory. 

In  charging,  the  boxes  must  be  only  half  filled,  as 
the  residue  of  the  acetylene  production  has  a  much 
larger  volume  than  the  original  quantity  of  carbide. 
If  these  boxes  are  filled  with  too  much  carbide,  the 
pressure  produced  by  the  increase  in  volume  of  the 
mass  might  cause  them  to  burst. 

Further,  this  pressure  from  within  will  compress  the 
outer  layer  of  the  lime-sludge  firmly  against  the  walls 


12 


AUTOGENOUS  WELDING  AND  CUTTING 


K- ---2400 


FIG.  8.  —  Vertical  and  horizontal  cross  sections  of  large  stationary 
"carbide  to  water"  acetylene  generator.  (Dimensions  shown 
in  millimetres.) 


ACETYLENE  MANUFACTURE  AND  APPARATUS       13 


of  the  box  preventing  the  access  of  water  to  the  car- 
bide, thereby  causing  overheating  of  the  gas.  The  tar 
products  then  forming  will  penetrate  the  layer  of  lime- 
sludge  and  transform  it  into  a  water  proof  mass  around 
the  remaining  carbide. 

In  such  cases  quantities  of  carbide  will  remain  un- 
used in 'the  box  and  will  be 
lost.  As  such  unused  por- 
tions of  carbide  are  usually 
thrown  away  with  the  resi- 
due into  drains  and  sewers, 
acetylene  will  form  there  and 
may  cause  severe  explosions. 

Effect  of  using  overheated 
Acetylene.  —  The  use  of  over- 
heated acetylene  easily 
causes  burned  welding  seams. 
Part  of  the  carbon  of  such 
acetylene  being  transformed 
into  tar  products,  the  re- 
mainder of  the  gas  forms  a 
mixture  with  free  hydrogen 
and  other  hydrocarbon 
products. 

In  a  molten  state  iron  ab- 
sorbs great  quantities  of  hy- 
drogen which  is  expelled  again  during  the  solidification 
of  the  metal,  resulting  in  a  foaming  of  the  welding  seam. 

During  this  foaming  of  the  welding  seam  the  iron  is 
divided  into  thin  films,  which  fall  back  into  the  molten 
mass  when  the  gas  bubbles  burst;  and  should  free 
carbon  be  present  in  the  flame  it  penetrates  into  these 
films  and  is  absorbed  by  the  iron.  This  results  in  the 
soft  metal  of  the  welding  seam  assuming  the  character- 
istics of  steel  and  in  some  cases,  the  properties  of  grey 


FIG.  9.  —  Cross  section  of  "carbide 
to  water"  acetylene  generator 
showing  jacket  for  protection 
against  frost. 


14 


AUTOGENOUS  WELDING  AND  CUTTING 


cast  iron.     Under  such  circumstances  the  welding  seam, 
upon  cooling,  becomes  hard  and  brittle. 

Another  consequence  of  the  use  of  overheated  acety- 
lene is  the  change  in  the  relative  proportions  of  the 

acetylene  and  the  oxygen  in 
the  welding  burner.  As  only 
the  volume  of  the  acetylene  is 
dependent  upon  the  injector 
pressure  in  the  burner,  while 
the  density  of  the  gas  varies 
with  the  temperature,  such  a 
change  produces  an  excess  of 
oxygen  in  the  flame;  and  this 
free  oxygen  enters  into  the 
molten  iron  and  burns  the  weld- 
ing seam. 

Gasifying  Dust  Carbide.  —  In 
acetylene  generators  in  which 
so  called  granulated  carbide  is 
introduced,  it  may  occur  that 
when  small  granulations  of  car- 
bide are  used,  the  heavier  carbide  sinks  in  the  water 
while  the  gas  bubbles  adhering  to  the  small  particles 
carry  them  again  to  the  surface.  The  bursting  of  these 
bubbles  liberates  the  gas  directly  into  the  gas  chamber 
and  the  remaining  carbide  particle  sinks  again  and 
the  process  is  repeated  until  the  carbide  is  entirely 
decomposed. 

The  continued  repetition  of  this  operation  produces 
gas  which  is  unsuitable  for  welding  purposes.  This 
occurs  particularly  when  using  dust  carbide  and  there- 
fore this  grade  should  not  be  used  in  carbide  to  water 
apparatus. 

To  gasify  dust  carbide  specially  constructed  acety- 
lene generators  must  be  used  in  which  the  carbide  is 


FIG.  10.  —  Cross  section  of 
"carbide  to  water"  acety- 
lene generator. 


ACETYLENE  MANUFACTURE  AND  APPARATUS       15 

introduced  in  closed  boxes  beneath  the  surface  of  the 
generator  water  so  that  it  is  only  there  that  the  trans- 
formation occurs. 

In  some   acetylene  generators  the   carbide  is  intro- 
duced  in   closed    boxes,    made   from   perforated   sheet 


FIG.  11.  —  Stationary  "carbide  to  water" 
acetylene  generator  where  carbide  is  intro- 
duced in  a  closed  drum  — 

B.    Carbide  delivery.      G.    Acetylene  chamber. 

K.  Water  filter.  R.    Pressure  regulator. 

T.    Delivery  pipe.  If.    Escape  vent. 

V-W.    Gasometer. 


iron,  which  boxes  are  passed  through  the  water  to  allow 
the  carbide  to  gasify  beneath  the  gas  collector.  With 
such  apparatus  the  gasometer  bell  must  not  be  loaded 
as  this  might  permit  the  pressure  to  increase  so  that 
the  gas  will  break  the  water  seal  of  the  gasometer  and 
escape  into  the  generator  room  causing  danger  of 
explosion. 

This  may  also  occur  if  the  resistance  which  the 
gas  has  to  overcome  in  its  passage  from  the  gene- 
rator to  the  gasholder  appreciably  increases.  The  con- 


16 


AUTOGENOUS  WELDING  AND  CUTTING 


necting  pipe  should  therefore  be  fitted  with  a  waste 
pipe  through  which  the  accumulated  water  may  be 
drained  off  and  this  should  be  considered  in  the  con- 
struction of  acetylene  generators. 

Water  to  Carbide  Generators.  —  A  widely  used  type 
of  apparatus  is  one  wherein  the  carbide  is  gasified  in 

special  chambers,  the 
water  supply  to  which 
is  regulated  by  the 
movement  of  the  gas- 
ometer bell.  A  retort 
containing  such  cham- 
bers can  either  be  ar- 
ranged in  the  lower 
part  of  the  gasometer 
or  be  provided  in 
special  generator  ves- 
sels. 

In  the  operation  of 
apparatus  of  this 
kind,  it  is  necessary 
to  insure  that  the  outlet  of  the  carbide  chambers  is  in 
proper  working  order  before  the  refilling  is  effected  and 
also  that  the  chambers  are  thoroughly  washed  and  dried 
before  recharging. 

If,  in  generators  of  this  type,  the  carbide  chamber  is  di- 
vided by  a  number  of  partitions,  not  more  than  5  pounds 
of  carbide  should  be  placed  in  any  individual  section. 
Should  a  greater  quantity  of  carbide  in  a  single  mass  be 
periodically  attacked  by  water,  the  influx  of  which  water 
is  stopped  when  the  gasometer  bell  reaches  a  certain 
height,  then  the  heat  which  will  continue  to  be  liberated 
may  lead  to  spontaneous  combustion  upon  the  opening 
of  the  chamber;  the  atmospheric  air  entering  and  form- 
ing with  the  acetylene  an  explosive  mixture. 


FIG.  12. —  Cross  section  of  portable  "car- 
bide to  water"  acetylene  generator 
where  carbide  is  introduced  in  a  closed 
box. 


ACETYLENE  MANUFACTURE  AND  APPARATUS       17 


With    apparatus    of    this    kind    the    gasometer    bell 
must  be  sufficiently  large  to  take  up  the  entire  quantity 
of  gas  produced  by  the  decom- 
position of  the  carbide  contained 
in   each   chamber.     Should   the 
capacity  be  insufficient  then  ap- 
preciable  after-generation   of 
acetylene  would  occur  which  sur-     J(  | 
plus  of  gas  would  escape   and     Jz^ 
be  lost. 

Another  point  to  be  observed 
is  that  the  individual  sections 
are  not  more  than  half  filled  as 
the  residue  occupies  greater 
space  than  the  original  carbide 


and  consequently  stoppages  can  FIG.  13.  —  Cross  section  of 

"water  to  carbide"   acety- 
lene    generator      equipped 


with  automatic  water  feed. 
A.    Water  chamber. 


B. 

C. 


When  refilling  such  appara- 
tus, the  carbide  holders  must  be 
dry  and  it  is  advantageous  to 
provide  an  extra  set  of  contain- 
ers so  that  while  one  set  is  in 
use,  the  other  can  be  thoroughly 
cleaned  and  dried.  • 

Automatic  Water  Displace- 
ment Generators.  —  Another 
group  of  generators  is  of  the 
type  where  the  carbide  placed 
in  a  basket  or  similar  holder  is 
periodically  dipped  into  the  gen- 
erator water  and  withdrawn. 
This  can  be  effected  by  having 
the  carbide  container  firmly  built  into  the  gasometer  bell, 
so  that  the  carbide,  with  the  sinking  of  the  bell,  dips 
into  the  water.  Or  the  carbide  container  can  be  firmly 


Gas  chamber. 
Purifier. 

D-Di.    Gas  delivery. 
E\-E<i.    Carbide   in    multi- 

section  container. 
F-Fi-F2.    Built-in  container 

tube. 

G-Gi.    Tube  head  and  lock. 
H.   Water  supply. 
J  \-J-L.   Water  delivery  regu- 

lator. 

M  .    Water  delivery  pipe. 
Ni-N2.    Gas  delivery  pipe. 
O.    Gas  outlet. 
P.    Acetylene  delivery  pipe. 
Q.    Gas  vent. 
R.    Drain  cock. 
S.    Gas  valve. 
U.    Purifier  head. 


18 


AUTOGENOUS  WELDING  AND  CUTTING 


fixed  in  a  lower  water  vessel  which  is  hermetically  sealed 
and  is  simply  connected  with  the  upper  water  vessel  by 
means  of  a  vertical  pipe. 

When  using  such  apparatus  for  the  purpose  of  autog- 
enous welding  one  must  be  careful  that  too  great  heat- 
ing does  not  occur  as  otherwise  this  may  be  dangerous. 


FIG.  14.  —  Cross  section 
of  "water  to  carbide" 
acetylene  generator 
with  automatic  device 
for  regulating  th'e  water 
feed. 


FIG.  15.  —  Acetylene 
generator  for  the  use 
of  compressed  car- 
bide. 


Use  of  Beagid.  —  In  the  place  of  the  carbide  in  gen- 
eral commercial  use,  one  can  also  use  in  water  displace- 
ment apparatus  of  this  kind,  compressed  carbide 
known  under  the  name  " Beagid"  and  similar  prepara- 
tions, which  is  a  mixture  of  carbide  and  a  substance 
soluble  in  water.  This  mixture  has  the  property,  when 
periodically  dipped  in  water,  of  loosening  off  single 
grains  which  fall  to  the  bottom  of  the  water  supply, 
so  that  such  apparatus  is  very  similar  to  the  carbide 
to  water  design. 


ACETYLENE  MANUFACTURE  AND  APPARATUS      19 


With  all  acetylene  apparatus  careful  cleanliness  and  at- 
tention to  the  prescribed  details  is  of  great  importance. 

If   in    an   acetylene    generator   of   the    carbide-water 
type  too  great  quantitites  of  carbide  are  gasified  with- 
out the  residues  being  removed  and  the 
generator  water  being  renewed,  sufficient 
heating  may  ensue  so  that,  with  the  open- 
ing of  the  apparatus  and  the  entrance  of 
atmospheric  air,  spontaneous   combustion 
may  be  caused. 

Dissolved  Acetylene.  —  For  the  purpose 
of  autogenous  welding,  acetylene  dissous, 
or  dissolved  acetylene,  is  also  much  used. 
In  its  preparation,  special  steel  bottles, 
destined  for  this  purpose,  are  filled  up  to 
the  top  with  a  porous  substance  and  the 
bottles,  so  filled,  are  heated  in  furnaces  suf- 
ficiently to  expel  every  trace  of  moisture. 
The  bottles  are  then  filled  with  liquid  ace- 
tone and  by  strict  observance  of  definite 
precautionary  methods,  acetylene  gas  is 
pumped  into  them  (Fig.  16). 

Other  systems  of  using  dissolved  acety- 
lene have  been  introduced  recently,  where 
steel  bottles  are  filled  with  a  fibrous  or 
other  porous  substance  and  then  treated  in      section  of 
a  manner  similar  to  the  above  process. 

Dissolved  acetylene  can  be  used  in  ordi- 
nary workshops  without  any  danger,  yet  a  steel  bottle 
filled  with  it  must  not  be  subjected  to  any  heating.  It 
is  therefore  necessary  to  take  care  that  they  are  not 
placed  near  any  furnace  or  other  hot  place  and  that  they 
are  protected  from  the  rays  of  the  sun. 

Special  welding  burners  and  special  pressure  reducing 
valves  must  be  used  for  acetylene  dissous. 


acetylene  dis- 
sous bottle. 


20  AUTOGENOUS  WELDING  AND  CUTTING 

In  using  it  for  welding  in  powerful  burners,  the 
acetone  will  also  be  drawn  out  with  the  escaping  acety- 
lene. This  makes  it  necessary  with  the  heavier  weld- 
ing work  to  couple  together  several  bottles  by  means 
of  special  fittings  and  to  place  the  pressure  reducing 
valve  in  the  common  outlet.  When  doing  particularly 
heavy  work  from  three  to  four  bottles  are  sometimes 
in  simultaneous  use. 

Chemical  Purifying.  —  In  the  manufacture  of  acety- 
lene, the  raw  material  used  for  the  production  is  not 
chemically  pure,  and  as  a  result  other 
gases  and  principally  sulphuretted  hy- 
drogen and  phosphuretted  hydrogen  are 
produced. 

The  quality  of  carbide  now  in  general 
commercial  use  is  such  that  the  impuri- 
ties from  this  cause  do  not  exceed  0.05% 
Flcal17p^ifiehreus-    sulphuretted  hydrogen  and  0.05%  phos- 
ing  hygroscopic    phuretted  hydrogen. 

cleansing  mass.  ot    i    i  111  •  i    i  i        • 

Sulphuretted  hydrogen  is  soluble  in 
water  and  is  therefore  retained  by  the  generator  water 
in  the  apparatus  in  which  periodically  small  amounts  of 
carbide  are  thrown  into  a  large  excess  of  water.  For 
this  reason,  with  such  apparatus,  only  the  phosphuretted 
hydrogen  need  be  given  consideration. 

Phosphuretted  hydrogen  has  a  pronounced  affinity 
for  oxygen  and  therefore  if,  for  autogenous  welding, 
acetylene  with  low  phosphuretted-hydrogen  content  is 
used,  this  latter  gas  will  act  as  a  reduction  medium 
for  the  metal  of  the  welding  seam.  The  phosphuretted 
hydrogen  will  combine  with  the  oxide  of  the  metal  form- 
ing phosphoric  acid. 

For  this  reason,  no  harm  can  result  when  using  cor- 
rectly dimensioned  carbide  to  water  apparatus,  not  to 
fill  the  purifier  with  chemical  purifying  mass;  such 


ACETYLENE  MANUFACTURE  AND  APPARATUS       21 

mass  however  may  be  used  to  advantage  for  drying 
the  acetylene. 

It  is  a  different  matter  with  the  water  to  carbide 
and  water  displacement  generators,  as  in  such  ap- 
paratus a  sufficient  amount  of  water  is  not  available 
for  thoroughly  absorbing  the  sulphuretted  hydrogen 
formed. 

It  is  therefore  necessary  to  provide  another  absorbing 
or  oxidizing  medium  and  when  using  such  apparatus 
care  must  be  taken  regarding  the  proper  use  and  re- 
newal of  the  chemical  purifying  mass.  Such  purify- 
ing masses  are  manufactured  on  the  base  of  chlor  or 
chromic-acid  preparations. 

When  using  hygroscopic  masses  in  an  acetylene  puri- 
fying apparatus  (Fig.  17)  it  is  advan- 
tageous to  let  the  acetylene  flow  from 
top  to  bottom  in  the  purifier,  while  with 
the  non-hygroscopic  masses,  the  flow  of 
the  gas  is  from  bottom  to  top  (Fig.  18). 

Mechanical  Purifying.  —  In  all  acety- 
lene  generators,    lime  dust  is  carried 

FIG.  18.  —  Chemical 

away  during  the  transformation  of  the      purifier  using  non- 
carbide  and  it  is  important  that  this      hygroscopic  cleans- 
ing mass. 
dust  should  be  removed  from  the  gas. 

If  this  is  not  done,  the  countless  molecules  of  lime  taken 
away  with  the  gas  will  be  blown  through  the  welding 
flame  and  become  embodied  in  the  material  of  the  weld- 
ing seam,  which  leads  to  a  very  appreciable  weakening 
of  the  metal. 

In  order  to  avoid  this,  a  dust  filter  should  be  ar- 
ranged in  front  of  each  individual  welding  place.  This 
dust  filter  can  be  constructed  of  two  plate-shaped 
metal  sheets  fitted  with  couplings  for  the  gas  inlet 
and  outlet  pipe.  The  edges  of  these  plates  should  be 
firmly  fastened  together  having  between  them  a  dia- 


22  AUTOGENOUS  WELDING  AND  CUTTING 

phragm    of    cloth    or    other    permeable    body    for    the 
filtration  of  the  gas  (Fig.  19.). 

As  a  filtering  medium,  a  fine  mesh  linen  may  be  used 


FIG.  19.  —  Cross 
section  of  dust 
filter. 


yet  care  must  be  taken  when  using  this  that  the  chem- 
icals in  the  cloth  have  been  previously  removed  by 
washing.  Such  filters  must  be  periodically  cleaned, 
which  can  be  done  by  removing  the  lime  dust  from  the 
diaphragm  by  means  of  a  brush. 


X 

CHAPTER  III 
OXYGEN    MANUFACTURE    AND    APPARATUS 

OXYGEN  used  for  autogenous  welding  purposes  is 
commonly  purchased  in  steel  bottles.  The  initial  pres- 
sure of  the  gas  in  these  bottles  is  150  atmos.  (2200 
Ibs.  per  sq.  in.)  and  when  filled,  they  must  not  be 
thrown  about  or  exposed  to  high  temperatures. 

At  the  crown  of  the  bottle,  the  effective  contents 
are  usually  stenciled  in  litres  and  if  this  capacity 
figure  is  multiplied  by  the  pressure  in  atmospheres, 
shown  by  the  gauge,  the  result  will  be  the  volume  of 
free  oxygen  in  the  cylinder. 

In  order  to  calculate  the  quantity  of  oxygen  used  for 
any  particular  work,  the  contents  of  the  cylinder  are 
calculated  in  the  beginning  and  after  the  work  is  finished, 
the  difference  being  the  quantity  of  oxygen  used. 

Up  to  the  present  time  there  does  not  exist  a  gas 
meter  capable  of  satisfactorily  measuring  gas  flowing 
under  such  high  pressures. 

Oxygen  Manufacture.  —  The  oxygen  used  for  the 
purpose  of  autogenous  welding  is  either  produced  by 
means  of  the  rectification  of  liquid  air,  the  electrolytic 
decomposition  of  water,  or  by  one  of  the  various  chemical 
processes.  The  last  named  produce  oxygen  of  different 
degrees  of  purity. 

For  autogenous  welding  and  cutting  it  is  advanta- 
geous to  have  oxygen  of  the  highest  purity  and  it  is  of 
advantage  to  be  able  to  determine  the  purity  of  the 
gas  used.  The  impurity  consists  in  liquid  air  oxygen, 
of  nitrogen  and  in  electrolytic  oxygen,  of  hydrogen. 

23 


24 


AUTOGENOUS  WELDING  AND  CUTTING 


Testing  the  Oxygen.  —  For  testing  the  purity  of 
the  gas,  a  graduated  glass  burette  is  filled  with  oxygen 
and  with  the  upper  end  closed,  the 
lower  end  of  the  burette  is  dipped  into 
a  vessel  containing  a  substance  which 
will  absorb  oxygen  but  not  its  impu- 
rities. This  absorbing  medium  will 
then  rise  in  the  burette  and  in  a  few 
minutes  the  degree  of  purity  of  the 
oxygen  can  be  read  on  the  divisions 
of  the  tube  (Fig.  20). 

A  satisfactory  fluid  for  testing  the 
purity  of  oxygen  by  absorption  is  pre- 
pared by  dissolving  30  weight  units  of 
pyrogallol  in  60  units  of  warm  water 
and  mixed  with  160  units  of  a  1  to  2 
solution  of  caustic  potash. 

Liquid  Air  Process.— The  most  com- 
mon system  for  the  production  of  oxy- 
gen is  the  air  liquifying  and  distillation 
process. 

Air  is  a  mechanical  mixture  of  about 
21%  of  oxygen  and  79%  of  nitrogen. 
If  atmospheric  air  is  compressed  at 
high  pressure  by  several  stages  of  com- 

FIG.  20. —Cross  sec- 
tion   of    apparatus   Passion  and  the  heat  is  removed  be- 

for  testing  the  purity  tween  each  stage  of  compression  by 
suitable  apparatus,  the  air  gradually 
reaches  a  state  of  great  density.  With  further  decrease 
in  temperature,  as  will  occur  when  such  air  under  high 
pressure  is  exhausted  through  a  throttle  valve  into  a 
space  of  lower  pressure,  a  liquifying  of  the  air  will  take 
place.  The  liquifying  of  atmospheric  air  occurs  at  a 
temperature  of  -316°  F. 

As  such  liquid  air  consists  of  a  mechanical  mixture 


OXYGEN  MANUFACTURE  AND  APPARATUS 


25 


A 

(fc$\ 


of  nitrogen  and  oxygen  and  the  boiling  point  of  nitro- 
gen is  at  -320°  F.  and  that  of  oxygen  at  -297°  F.  there 
is  a  difference  of  23  degrees  between  the  critical  points 
of  the  two  gases. 

In  the  usual  oxygen  production  plants,  the  pipe  for 
supplying  the  compressed  air  to  the 
decompression  valve  of  the  air  liqui- 
fying apparatus  is  led,  in  a  coiled 
copper  pipe,  through  the  container  in 
which  the  liquid  air,  collects.  Thus 
the  compressed  air  before  its  actual 
liquification,  serves  to  heat  the  liquid 
air  produced,  while  at  the  same  time 
an  equivalent  amount  of  cold  is  given 
off  from  the  liquid  to  the  compressed 
air. 

Consequently,  the  liquid  air,  as  the 
result  of  this  heating,  must  vaporise 
and  as  the  boiling  points  of  the  two 
component  parts  are  somewhat  differ- 
ent in  temperatures,  the  bulk  of  the 
vapor  must  be  nitrogen. 


If  these  gases  rich  in  nitrogen  are  FlCL  21_  Oxygen  bot. 
brought  into  contact  with  large  sur-  tie  and  protection 
faces  of  fresh  incoming  liquid  air,  in 
a  manner  similar  to  the  distillation  of  alcohol,  an  en- 
riching of  the  remaining  liquid  with  the  liquid  oxygen 
occurs  while  at  another  point  of  the  apparatus  the  tech- 
nically pure  nitrogen  vapor  escapes. 

It  is  on  this  process  that  the  design  of  the  air  liquify- 
ing apparatus  for  producing  oxygen  is  constructed. 
In  such  process  1  to  3  H.P.  hours  are  required  for  the 
production  of  one  cubic  metre  (35  cubic  feet)  of  oxy- 
gen, according  to  the  size  of  the  plant. ' 

Electrolytic  Process.  —  In   the   case   of   tjie   electro- 


26  AUTOGENOUS  WELDING  AND  CUTTING 

lytic  production  of  oxygen  a  separation  of  water  into 
its  component  parts,  i.e.  hydrogen  and  oxygen,  is  ef- 
fected. While  atmospheric  air  is  a  mechanical  mixture, 
the  component  parts  of  water  are  in  chemical  combina- 
tion and  therefore  greater  energy  is  required  to  effect 
the  separation. 

The  production  of  1  cubic  metre  of  oxygen  by  the 
electrolytic  method  requires  12  to  13  H.P.  hours 
and  it  is  evident,  from  this  large  power  requirement, 
that  such  process  can  only  be  advantageous  and  eco- 
nomical under  particular  conditions,  when  compared 
with  the  liquid  air  process. 

Wherever  there  is  use  for  the  electrolytically  pro- 
duced hydrogen,  as  for  example  in  the  soap  industry, 
the  electrolytic  process  of  the  production  of  oxygen 
possesses  great  economic  possibilities. 

Chemical  Processes.  —  There  exists  other  different 
chemical  processes  for  the  manufacture  of  oxygen, 
which  however  are  not  of  great  practical  importance  on 
account  of  their  great  cost.  For  this  reason  it  is  im- 
practical to  devote  sufficient  space  herein  to  deal  with 
this  subject  in  an  exhaustive  manner. 

On  account  of  the  commonly  used  size  of  40  litres 
capacity  for  steel  bottles  for  the  shipment  of  oxygen 
and  owing  to  the  general  filling  pressure  of  150  atmos- 
pheres, every  bottle  of  commercial  oxygen  necessi- 
tates a  shipping  weight  of  12  kilos  (26.5  Ibs.)  per  cubic 
metre.  The  transportation  charges  therefore  form  a 
considerable  item  in  the  calculation  of  the  price  of 
oxygen. 

Oxygen  Valves.  —  The  oxygen  bottles  in  commercial 
use  are  provided  with  a  screw  cut-out  valve  having  a 
side  connection  for  the  pressure  reducing  valve.  In 
order  to  protect  the  cut-out  valve  during  transport,  it 
is  covered  with  a  steel  screw  cap  and  the  side  connec- 


OXYGEN  MANUFACTURE  AND  APPARATUS 


27 


tion  is  protected  by  means  of  a  brass  cap   (Figs.  21, 
22  and  23). 

If,    in    an    autogenous   welding   plant,    it   should   be 
noticed  the  cut-off  valve  on  the  bottle  is  leaking,  the 


FIG.  22.—  Outlet  fittings  of 
oxygen  bottle. 


FIG.  23.  —  Cross  section  of 
high  pressure  valve  for 
oxygen  bottle. 


oxygen  company  should  be  advised  at  once  and  such 
faulty  bottle  be  returned  to  the  factory. 

Taking  apart  and  repairing  these  fittings  should  be 
avoided,  for  if  traces  of  oil  or  fat  get  into  the  bore, 
spontaneous  combustion  may  occur,  which 
under  certain  conditions  may  cause  explo- 
sions and,  even  in  the  most  favourable 
circumstances,  will  lead  to  the  destruction 
of  the  valves. 

For  autogenous  welding,  oxygen  is  used 
under  a  pressure  varying  in  accordance  FlG-   24-  —  Gas 

-,i     .1         '          f  ±1       i  i  ^  r      pressure  gauge. 

with  the  size  of  the  burner,  between  0.5 

and  3.0  atmospheres  (7  to  42  Ibs.  per  sq.   in.). 

The  initial  pressure  of  the  oxygen  in  the  bottles,  of 


28  AUTOGENOUS  WELDING  AND  CUTTING 

150  atmospheres,  gradually  decreases  with  the  use 
of  gas  and  to  secure  a  constant  working  pressure,  the 
common  pressure  reducing  valve  is  used. 

Pressure  Reducing  Valves.  —  A  valve  of  this  kind 
for  oxygen  consists  of  a  metal  .body  with  a  bore  for 
the  escaping  oxygen  on  which  a  pressure  gauge  is  fixed 
which  constantly  shows  the  pressure  in  the  cylinder 
(Figs.  24,  25  and  26). 

The  exit  of  the  oxygen  is  regulated  by  a  hard  rubber 
body  connected  to  a  two  part 
lever  which  rubber  body  is, 
by  means  of  a  spring,  pressed 
against  the  oxygen  outlet 
nozzle. 

Set  against  the  working  of 
this  spring  is  a  second  spring 

FIG.  25. -Cross  section  of  which  is  separated  from  the 
pressure-reducing  valve  for  valve  chamber  by  a  dia- 
oxygen  bottle.  phragm,  so  that  the  interior 

is  shut  off  from  the  atmosphere  in  a  gas  tight  manner. 

This  second  spring  can,  by  means  of  an  adjustable 
screw,  be  more  or  less  compressed,  so  that  against  the 
pressure  of  the  first  spring  a  resistance  can  be  regulated 
from  the  outside.  Consequently  the  two  springs  form 
two  forces,  of  which  one  can  be  regulated  as  desired. 

At  the  interior  between  the  oxygen  valve  and  the 
diaphragm,  a  second  pressure  gauge  is  attached,  while 
at  the  side  of  the  valve  chamber  is  placed  the  oxygen 
outlet  connection.  This  second  gauge  shows  the  pres- 
sure under  which  the  oxygen  is  fed  to  the  burner. 

In  another  design  of  valve,  the  regulating  of  the 
burner  pressure  is  effected  by  means  of  a  diaphragm 
controlled  by  a  suspension  spring  so  that  a  body  is 
interposed  through  which  a  shaft  is  pushed  more  or 
less  into  the  bore  of  oxygen  outlet  orifice. 


OXYGEN  MANUFACTURE  AND  APPARATUS          29 

If,  in  an  autogenous  welding  plant,  any  trouble 
should  occur  with  the  pressure  reducing  valve,  it  is 
to  be  recommended  that  this  be  removed  and  re- 
turned to  the  manufacturer  for  repairs. 

Before  fitting  the  reducing  valve  to  a  bottle  of  oxy- 
gen, care  must  be  taken  to  see  that  any  dust  or  other 
matter  in  any  of  the  connections  is-  blown  out.  This 


M. 


FIG.  26. —  Cross  section  showing  details  of  construction 
of  pressure-reducing  valve. 

can  be  done  by  a  quick  opening  and  closing  of  the  cut- 
out valve,  as  any  foreign  matter  may  cause  trouble 
if  it  gets  into  the  valve  fittings.  It  should  also  be  ob- 
served that  all  connection  joints  are  in  good  condition. 
In  placing  an  oxygen  bottle  in  service  it  is  advanta- 
geous to  have  the  cut-out  valve  opened  slowly  and  not 
too  suddenly,  and  the  workman  should  avoid  standing 
directly  in  front  of  the  reducing  valve  during  this  oper- 
ation. In  several  cases  it  has  occurred  that  the  high 
pressure  of  the  oxygen  bottle  suddenly  turned  on  has 


30  AUTOGENOUS  WELDING  AND  CUTTING 

burst  the  reducing  valve  owing  to  bad  threads  or  faulty 
material,  in  which  cases  the  front  part  of  the  valve  was 
thrown  out  inflicting  serious  injury  to  the  operator. 

Repairs  to  pressure  reducing  valves  should  only  be 
done  in  shops  specially  fitted  up  for  such  work,  for 
these  valves  must  stand  the  pressure  of  150  atmos. 
and  therefore  the  metal  parts  are  subjected  to  severe 
strains. 


CHAPTER   IV 
GAS   MAINS    AND    FITTINGS 

IT  is  very  important  that  the  piping  for  conducting 
acetylene  through  an  autogenous  welding  shop  be  of 
sufficient  diameter,  for  when  this  is  not  the  case,  a 
burning  of  the  welding  seam  may  occur  if  an  un- 
usual number  of  welding  burners,  or  burners  with  a  larger 
acetylene  consumption,  are  placed  in  operation. 

Gas  Mains.  —  In  a  properly  arranged  welding  shop 
a  large  gas  main  is  laid  through  the  workshop,  in  which 
branch  pipes  are  provided  for  each  individual  welding 
station. 

With  low  pressure  acetylene  apparatus,  the  pressure 
of  the  acetylene  is  generally  of  100  m/m  water  column 
or  .01  atmos.  (.147  Ibs.  per  sq.  in.)  while  the  pressure 
of  the  oxygen  may  under  certain  circumstances  be  2 
atmos.  (29.4  Ibs.  per  sq.  in.).  The  welding  burners 
are,  following  these  conditions,  constructed  on  the 
injector  principle. 

Back  Firing.  —  If,  during  operation,  the  bore  in  the 
burner  tip  becomes  choked,  as  may  happen  through 
the  molten  iron  spurting  into  the  nozzle,  then  the 
oxygen,  being  under  high  pressure,  will  recede  into  the 
acetylene  supply  which  is  under  low  pressure. 

Now  should  incandescent  particles  of  soot  be  carried 
back  by  the  oxygen  stream,  an  explosion  will  occur, 
if,  in  the  acetylene  gas  main,  there  should  be  a  suitable 
place  for  the  formation  of  an  explosive  oxy-acetylene 
mixture.  Such  explosion  may  have  very  serious  re- 

31 


32 


AUTOGENOUS  WELDING  AND  CUTTING 


suits,  especially  if  the  incandescent  matter  penetrates 
as  far  as  the  acetylene  generator. 

Safety  Devices.  —  For  this  reason  it  is  necessary  to 
provide  against  such  possibilities  by  inserting  a  back- 
flash  prevention  device  in  the  feed  pipe  of  the 
bustible  gases. 


FIG.  27.  —  Cross  section  of 
water  seal  —  Fouche  sys- 
tem. 

A.  Inlet  valve. 

B.  Outlet  valve. 

C.  Water  entrance. 

D.  Gas  chamber. 

E.  Drain  cock. 

F.  Pressure  regulator. 


FIG.  28.  —  Cross  section 
of  water  seal  equipped 
with  whistle  signal. 

A.  Gas  inlet. 

B.  Gas  chamber. 

C.  Gas  delivery  pipe. 

D.  Water  seal. 

E.  Gas  reservoir. 
G.  Container. 

H.  Container  cap. 
/.  Whistle  signal. 
K.  Drain  cock. 


The  most  reliable  type  of  such  a  back-flash  safety 
device  is  constructed  in  the  form  of  a  water  seal,  or 
trap,  and  arranged  at  each  individual  welding  station 
so  that  the  acetylene,  en  route  to  the  burner,  is  con- 
ducted through  this  water  supply  (Figs.  27,  28,  29 
and  30). 


GAS  MAINS  AND  FITTINGS 


33 


The  welder  must  see  before  the  commencement  of 
each  welding  period  that  a  sufficient  supply  of  water 
is  present  in  the  trap,  which  can  generally  be  done  by 
opening  a  test  cock  provided  for  the  purpose. 

Connection  Hose.  —  For  supplying  the  acetylene 
and  oxygen  to  the  welding 
burner,  either  rubber  or  flexi- 
ble metal  hose  is  used.  The 
diameter  of  such  hose  should 
not  be  less  than  6  m/m  (J  in.) 
for  oxygen  and  8  m/m  (TS  in.) 
for  acetylene. 

As  the  acetylene  is  under  a 
low  pressure,  ordinary  rubber 
hose  of  sufficient  strength  to 
prevent  leaking  may  be  em- 
ployed. However,  should  too 
soft  a  rubber  hose  be  used,  it 

FIG.    29.  —  Cross    section     of 
Will    easily    flatten,     in     COnse-         water    seal  —  Herzfeld    sys- 

quence  of  the  suction  influence       tem- 

„  ..  ,  A.    Inlet  valve. 

of  the  oxygen,  and  cause  sput- 
tering in  the  burner. 

Rubber  Hose.  —  Bursting 
of  the  rubber  generally  occurs  where  the  hose  is 
drawn  over  the  connecting  nipples  but  this  may  be 
prevented  by  winding  steel  wire  over  that  portion  of 
the  hose. 

For  oxygen,  the  ordinary  hose  with  hemp  lining  is 
used  as  this  has  sufficient  strength  for  the  high  pressure 
of  the  gas.  Hose  wrapped  with  flexible  wire  coil  may 
also  be  used  to  advantage. 

If  the  fittings  for  the  hose  connections  are  the  com- 
mon sleeve  couplings,  care  must  be  taken  that  the 
joints  are  kept  in  good  condition. 

Defective  rubber  hose  may  be  repaired   by   cutting 


E.  Drain  cock. 

F.  Outlet  valve. 

H.   Pressure  chambers. 


34 


AUTOGENOUS  WELDING  AND  CUTTING 


out  the  leaking  part  and  connecting  the  two  ends  with 
a  suitable  piece  of  metal  pipe  (Fig.  31). 


FIG.  30.  —  Cross  section  of  water  seal 
equipped  with  gas  pressure  chamber. 

Metal  Hose.  —  When  metal  hose  is  used,  care  must 
be  taken  that  the  packing  of  the  hose  spirals  which  is 
done  with  a  rubber  packing,  is  not  touched  with  a 


FIG.  31 . —  Cross  section  of 
repaired  rubber  hose. 


welding  flame.     In  this    case  the  rubber  packing  will 
burn,  causing  a  leak  which  cannot  be  repaired. 


CHAPTER  V 
AUTOGENOUS    WELDING    BURNERS 

AN  autogenous  welding  burner  is  an  extremely  sensi- 
tive  apparatus,  whose  good  working  is  dependent  upon 
the  exactness  of  its  construction.  Consequently  it  is 
often  found  that  those  with  cheaper  first  cost  are  the 
most  expensive  to  operate. 

Equal  Pressure  Burners.  —  In  using  a  combustible 
gas  supplied  to  the  burner  at  a  pressure  equal  to  that 
of  the  oxygen,  it  is  sufficient  if  ^ 
the  burner  is  fitted  with  a  simple 


mixing  chamber  into  which  the 

two  gases  are  conducted  through    FlG  32  _  piagram  showing 

Converging  bores  (Fig.  32).  gas  feed  in  an  autogenous 

For  using  acetylene  dissous  welding  burner' 
the  burners  are  so  constructed  that  the  acetylene  is  led 
through  a  filtering  substance  usually  situated  in  a  cham- 
ber in  the  handle  of  the  burner.  This  serves  to  prevent 
the  flame  getting  behind  the  burner  and  reaching  the 
acetylene  bottle. 

Should  the  acetylene  used  for  autogenous  welding 
be  drawn  from  the  usual  acetylene  generator,  then 
other  conditions  will  exist,  which  must  be  considered 
in  the  construction  of  the  burner. 

Such  apparatus  give  off  the  acetylene  gas  at  the 
low  pressure  of  about  100  m/m  water  column,  or  .01 
atmospheres.  This  low  pressure  does  not  allow  the 
speed  of  the  explosive  gases  to  be  sufficiently  high,  to 
exceed  the  combustion  speed  of  the  oxy-acetylene  mix- 

35 


AUTOGENOUS  WELDING  AND  CUTTING 


ture    in  the  flame,    and   this   condition   would   induce 
continual  back  fire  and  explosion  in  the  burner. 

Injector  Burners.  —  In  order  to  avoid  this,  the  oxy- 
gen must  be  given  sufficient  pressure  to  produce  a  suc- 
tion effect  upon  the  acetylene  supply  by  means  of  an 
injector  arrangement  in  the  welding  burner. 


FIG.  33. —  Oxy-acetylene  welding  burner. 

An  oxy-acetylene  burner  is  a  very  sensitive  appara- 
tus and  the  greatest  care  must  be  exercised  in  its  man- 
ufacture. Since  the  first  satisfactory  welding  burners 
were  constructed  by  the  French  engineer,  Edward 
Fouche,  burner  manufacture  has  developed  extensively 
and  has  led  to  the  design  of  various  styles  of  welding 
burners  (Figs.  33,  34,  35,  36,  37). 


FIG.  34. —  Oxy-acetylene  welding  burner. 

Adjustable  Burners.  —  For  welding  in  large  works,  a 
different  burner  is  used  for  each  individual  thickness 
of  material.  Burners  in  which  the  oxygen  nozzle  open- 
ing can  be  regulated  by  a  needle  valve,  have  been  in- 


AUTOGENOUS  WELDING  BURNERS 


37 


FIG.  35. —  Oxy-acetylene  welding  burner. 

troduced    by    different    makers,    but    have    not    proved 
satisfactory. 

In  small  shops,  as  for  example,  a  locksmith,  burners 
are  used  on  which  interchangeable  tips,  fitted  with  a 
fixed  oxygen  injector  device,  can  be  attached. 


FIG.  36. —  Oxy-acetylene  welding  burner. 

Much  trouble  is  caused  by  welding  burners  which 
have  not  carefully  and  precisely  made  bores.  In  many 
cases,  after  the  burners  have  been  in  use  for  some 
time,  changes  in  the  flame  will  occur  in  consequence 
of  unequal  expansion  of  metal  from  the  heat,  and  this 
makes  it  necessary  to  repeatedly  cool  such  burners. 


FIG.  37. —  Oxy-acetylene  welding  burner. 

Flame  Adjustment.  —  In  the  use  of  autogenous  weld- 
ing burners  it  is  necessary  to  watch  that  the  welding 
flame  is  correctly  adjusted.  The  correct  adjustment  is 
secured  when  the  inner  cone  of  the  flame  has  the 
greatest  possible  length  and  its  contour  is  sharply 
defined  against  the  outer  part  of  the  flame  (Fig.  38). 


38  AUTOGENOUS  WELDING  AND  CUTTING 

If  an  illuminating  mantle  is  formed  around  the  inner 
cone,  there  is  a  surplus  of  acetylene  (Fig.  39).  If  the 
inner  cone  is  shortened  and  transformed  in  color,  from 
a  dazzling  white  to  a  violet,  then  there  is  a  surplus  of 
oxygen  (Fig.  40).  In  both  cases  the  welder  will  be 
able  to  bring  the  flame  to  its  correct  proportions  by 
suitable  adjustment  of  the  gas  feed  on  the  burner. 

Oxidising  Flame.  —  A  surplus  of  oxygen  in  the  flame 
causes  a  burning  of  the  welding  seam  or  leads  to  the 
metal  being  overheated;  which  is  no  more  or  less  than  a 
minor  degree  of  burning. 


FIG.  38.  — Correctly  adjusted  or  neutral  oxy-acetylene  welding  flame. 

When  welding  mild  steel,  if  a  very  lively  spray  of 
sparks  is  in  evidence  it  is  a  sign  that  a  burning  of  the 
welding  seam  is  occurring,  especially  if  the  sparks,  so 
thrown  out,  burst  at  the  end  of  their  flight.  When 
welding  with  a  correctly  adjusted  flame  the  sparks 
will  retain  a  distinct  ball  shape  form. 


FIG.  39.  —  Carbonizing  welding  flame,  i.e.  with  excess  of  acetylene. 

When  the  former  appearance  occurs  in  welding  it 
is  necessary  either  to  decrease  the  oxygen  supply,  which 
can  be  effected  by  suitably  adjusting  the  screw  of  the 


AUTOGENOUS  WELDING  BURNERS  39 

pressure  reducing  valve,  or  to  increase  the  acetylene 
supply  by  adjusting  the  acetylene  valve  on  the  welding 
burner. 

Carbonizing  Flame.  —  If  the  inner  cone  of  the  weld- 
ing flame  loses  its  distinct  outline  and  is  surrounded 
by  a  faint  light  mantle,  it  is  a  sign  that  there  is  a 
surplus  of  acetylene  in  the  flame. 

Then  it  is  necessary  to  either  reduce  the  flow  of  acet- 
ylene until  a  normal  welding  flame  is  secured,  or  to  set 
the  pressure  reducing  valve  on  the  oxygen  bottle  to  a 
higher  pressure,  resulting  in  a  larger  oxygen  supply, 
so  that  the  correct  proportions  of  the  mixture  will  be 
obtained. 

An  excess  of  acetylene  in  the  welding  flame  may  lead 
to  hardening  of  the  welding  seam,  in  the  case  of  mild 
steel,  or  wrought  iron,  as  carbonization  of  the  iron 
occurs,  in  consequence  of  the  free  carbon  present  in 
the  flame. 


FIG.  40. —  Oxidizing  welding  flame,  i.e.  with 
excess  of  oxygen. 

As  already  stated,  the  burning  of  the  acetylene  in 
a  stream  of  oxygen,  is  a  two  phase  process  and  this 
circumstance  is  the  determining  factor  for  the  relative 
proportions  of  the  gases  fed  into  an  autogenous  welding 
burner. 

Any  welding  burner,  in  the  construction  of  which 
this  factor  has  not  been  taken  into  account,  will  lead 
to  faulty  welding  seams. 

Burner  Construction.  —  In  an  autogenous  welding 
burner,  a  throttle  point  is  provided  for  the  oxygen 


40  AUTOGENOUS  WELDING  AND  CUTTING 

injector,  where  the  diameter  of  the  bore  begins  to  in- 
crease. Beginning  with  the  widest  part  of  the  bore, 
a  conical  reduction  of  the  same  commences,  the  burner 
tip  ending  in  a  narrow  cylindrical  boring,  by  means 
of  which  the  issuing  mixture  of  the  gases  is  throttled 
so  that  the  velocity  of  the  escaping  gas  becomes  greater 
than  the  velocity  of  the  ignition  of  the  explosive  mix- 
ture. In  this  way  back  flashes  of  the  flame  into  the 
bore  of  the  burner  may  be  prevented  successfully. 

The  taper  of  the  bore  must  be  carefully  calculated 
and,  should  the  exit  nozzle  become  stopped,  the  use 
of  a  reamer  which  would  damage  the  bore  must  be 
avoided. 

The  tip  of  the  burner  is  usually  made  of  copper, 
while  the  other  portions  are  made  of  brass  or  malleable 
iron.  Brass  is  a  compound  of  copper  and  zinc,  two 
metals  which  have  different  melting  points. 

If  when  using  a  welding  burner,  a  back  firing  occurs, 
it  is  possible  that  the  flame  may  exist  in  the  interior 
of  the  welding  burner,  where  the  mixing  of  the  com- 
bustible gas  and  oxygen  is  effected.  Even  after  the 
dipping  of  the  nozzle  in  water  such  a  flame  may  con- 
tinue to  burn. 

With  common  oxy-hydrogen  burners,  such  a  flame 
melts  off  the  inner  nozzle  of  the  burner  which  is  usually 
made  of  iron.  On  this  account,  in  oxy-hydrogen  weld- 
ing plants,  a  good  supply  of  such  iron  nozzles  should 
be  available  so  that  the  welder  may  make  the  neces- 
sary renewal. 

In  oxy-acetylene  burners,  this  interior  burning  of 
the  flame  would  readily  melt  the  zinc  out  of  the  alloy 
metal  and  thus  cause  an  unevenness  in  the  interior  bore 
of  the  burner,  which  would  produce  eddies  in  the  flow 
of  the  gases. 

Mixing  of  Gases.  —  Some  investigators  have  shown 


AUTOGENOUS  WELDING  BURNERS  41 

that  immediately  behind  the  oxygen  nozzle  the  mixture 
of  the  two  gases  is  absolutely  complete.  Others  assert 
that  the  mixture  of  the  gases  is  more  or  less  complete 
at  the  exit  of  the  high  pressure  oxygen  nozzle,  the 
extent  of  the  mixture  being  dependent  upon  the  angle 
and  the  pressure  under  which  the  acetylene  is  fed; 
and  that  the  oxygen  current  draws  the  acetylene  with 
it,  in  eddies,  into  the  burner  nozzle  where  the  acetylene 
becomes  more  or  less  separated  by  centrifugal  force, 
so  that  it  comes  in  contact  with  the  inner  bore  of  the 
heated  burner  tips.  The  degree  of  expansion  of  the 
acetylene  thus  becomes  greater  than  that  of  the  oxygen 
and  this  serves  to  explain  the  difference  in  the  relative 
proportions  of  the  mixture,  which  occur  when  the 
burner  nozzle  becomes  heated. 

It  is  certain  that  with  various  types  of  burners  the 
relative  proportions  of  the  mixture  are  considerably 
altered  after  the  heating  of  the  burner.  There  are 
types  of  burners  where  these  changes  are  a  very  fre- 
quent and  unpleasant  occurrence  for  the  welder;  and 
in  this  case  the  cooling  must  extend  over  the  whole 
nozzle  body.  In  other  types  the  cooling  is  necessary 
only  when  the  burner  tip  has  become  so  hot  that  there 
is  danger  of  melting  off  the  copper  point. 

Cleaning  of  Burner.  —  During  autogenous  welding 
work,  drops  of  molten  metal  frequently  splash  into  the 
burner  nozzle  where  they  solidify  and  affect  the  opera- 
tion of  the  burner.  It  is  then  necessary  to  clean  the 
nozzle  either  with  a  sharpened  piece  of  wood  or  by 
means  of  a  spiral  fluted  reamer  which  exactly  fits 
the  bore. 

Back  Firing.  —  In  the  event  of  a  back  firing  of  the 
flame  into  the  interior  of  the  burner,  the  welder  should 
close  the  acetylene  valve  so  that  further  burning  is 
averted.  If  this  is  not  done  then  sparks  from  the 


42  AUTOGENOUS  WELDING  AND  CUTTING 

interior  flame  will  be  forced  through  the  nozzle  and  a 
rapid  and  intensive  heating  of  the  burner  will  take 
place. 

With  burners  having  interchangeable  nozzles,  it  is 
necessary  to  see  that  all  joints  and  fittings  are  in  good 
condition,  as  otherwise  very  serious  trouble  may  be 
experienced. 

In  various  types  of  burners  the  mixing  chamber  is 
located  in  the  handle  of  the  burner  while  a  thin  copper 
or  a  steel  pipe,  on  the  end  of  which  the  usual  copper 
nozzle  is  provided,  serves  as  a  mixing  chamber.  This 
copper  pipe  has  the  advantage  of  being  bent  as 
desired,  but  such  pipe  must  be  carefully  handled  as 
repeated  bendings  cause  much  damage. 

With  these  burners  the  mixing  chamber  is  outside 
the  limits  of  the  heating  zone  of  the  burner  and  this 
has  particular  technical  advantages. 

With  another  type  of  burner  the  oxygen  is  fed  into 
the  injector  by  means  of  a  small  copper  pipe  arranged 
spirally  around  the  burner  nozzle.  The  object  of  such 
arrangement  is  to  cool  the  burner  nozzle  by  absorb- 
ing the  heat  radiating  from  the  welding  place  and 
at  the  same  time  to  preheat  the  oxygen  led  to  the 
injector. 

This  preheating,  however,  causes  an  expansion  and 
consequently  increases  the  volume  of  oxygen  accord- 
ing to  the  degree  of  heat,  which  produces  changes  in 
the  relative  proportion  of  the  mixture  and  therefore 
in  the  effectiveness  of  the  burner. 

Gas  Consumption.  —  Manufacturers  of  autogenous 
welding  burners  have  taken  as  a  standard,  that  for 
each  millimetre  of  thickness  of  the  sheet  to  be  welded 
an  hourly  consumption  of  80  litres  of  acetylene  and 
100  litres  of  oxygen  is  necessary.  The  requirement 
on  this  basis  for  the  welding  of  a  sheet  f  inches  in  thick- 


AUTOGENOUS  WELDING  BURNERS  43 

ness,   would  be  an  hourly  consumption  of  33.8  cubic 
feet  of  oxygen  and  27  cubic  feet  of  acetylene. 

An  experienced  welder  works  to  advantage  by  using 
larger  burners  than  standard,  as  his  output  increases 
while  the  required  amount  of  gases  used  for  the  same 
length  unit  of  the  seam  diminishes.  «This  is  to  be  ex- 
plained by  the  fact  that  when  working  quickly  less 
heat  is  absorbed  by  the  metal  adjacent  to  the  welding 
seam. 


CHAPTER  VI 
• 
AUTOGENOUS    CUTTING    BURNERS 

THERE  are  three  kinds  of  autogenous  cutting  burners, 
viz: 

Cutting  burners  in  which  the  oxygen  is  taken  from 
a  central  nozzle  placed  concentric  with  the  annular 
nozzle  feeding  the  pure  combustible  gas  (Fig.  41). 


FIG.  41.  —  Vertical  and  horizontal  cross  sections  of 
autogenous  cutting  burner  having  central  oxygen 
nozzle  and  equipped  with  roller  attachment. 

Cutting  burners  constructed  similar  to  the  above, 
but  in  which  a  mixture  of  combustible  gas  and  oxygen 
is  fed  through  the  annular  nozzle  in  place  of  the  pure 
combustible  gas. 

Cutting  burners  composed  of  the  usual  type  of  weld- 
ing burner  with  an  oxygen  nozzle  arranged  at  the  side 
of  it  (Fig.  42). 

Theory  of  cutting.  —  Autogenous  cutting  is  based 
on  the  fact  that  iron  has  the  property  of  burning  in  an 

44 


AUTOGENOUS  CUTTING  BURNERS  45 

atmosphere  of  oxygen,  if  the  iron  is  brought  to  a  certain 
high  temperature. 

With  the  usual  cutting  burners,  the  regular  combus- 
tion flame  serves  for  the  local  heating  of  the  material 
while  the  oxygen  is  blown  in  a  compact  stream  upon 
the  heated  place. 

As  in  the  case  of  the  burning  of  any  other  com- 
bustible body,  heat  is  liberated  by  the  burning  of  the 
iron  which  raises  the  temperature  of  the  adjacent 
parts  of  the  iron  and  prepares  it  for  further  combustion. 
This  burning  can  only  occur  when  oxygen  of  sufficient 
mechanical  force  is  directed  on  to  the  hot  iron  and 
the  combustion  is  effected  in  the  direction  of  the  oxy- 
gen stream  through  the  total  thickness  of  the  body. 

In  this  manner  a  smooth  cut  is  obtained  and  with 
increasing  thickness  of  the  iron,  there  is  improvement 
in  cutting  effect. 

Volume  of  oxygen.  —  In  this  combustion  process 
the  oxygen  combines  with  the  molten  particles,  thrown 
off  by  the  speed  of  the  current,  to  form  iron  oxide. 
For  this  reason  the  quantity  and  current  velocity  of 
the  oxygen  must  be  greater  according  to  the  increasing 
thickness  of  the  metal  sheets. 

The  evenness  of  the  surface  of  an  autogenous  cut 
is  primarily  dependent  upon  the  compactness  of  the 
stream  of  oxygen.  It  is  also  dependent  upon  the  direc- 
tion of  the  current  remaining  constant. 

Guiding  Devices.  —  For  the  latter  reason  it  is  of 
advantage  to  fit  the  cutting  burner  with  a  mechanical 
guiding  device.  Guiding  by  hand  cannot  be  as  steady 
and  even,  as  with  a  mechanical  guide,  for  the  effect 
of  the  pulsating  of  the  blood  in  the  hand  is  sufficient 
to  produce  unevenness  in  the  surface  of  the  cut.  The 
more  even  the  guide,  the  better  the  cut  and  the  more 
economical  the  operation. 


46  AUTOGENOUS  WELDING  AND  CUTTING 

The  usual  guiding  device  for  autogenous  cutting 
burners  comprises  a  pair  of  rollers  mounted  on  the 
burner  nozzle.  These  rollers  should  be  so  arranged 
that  the  oxygen  nozzle,  especially  in  the  double  nozzle 
burners,  should  reach  about  5  m/m  nearer  to  the 
material  to  be  worked  on,  than  the  combustion  flame 
which  approaches  the  surface  to  be  worked  upon  at  a 
distance  of  5  m/m  (about  TS  inches). 

For  the  execution  of  circular  cuts,  a  guiding  device 
is  used,  composed  of  a  guide  rod,  to  one  end  of  which 
the  cutting  burner  is  fixed,  while  at  the  axis  of  the  rod, 
a  trammel  point  is  arranged  so  that  the  burner  can  be 
moved  around  a  given  centre. 

For  executing  irregular  cuts,  a  suitable  templet  is 
provided  along  which  the  burner  is  guided. 


FIG.  42. —  Cross  section  of  autogenous  cutting  burner 
having  an  independent  oxygen  nozzle. 


An  interesting  device  for  autogenous  cutting  con- 
sists of  placing  the  drawing  on  a  table  at  the  side  of 
the  work  bench  and  providing  a  suitable  connection 
for  the  cutting  burner.  Such  appliances  are  known 
in  the  United  States  as  the  Pantograph  and  Oxygraph 
cutters.  By  moving  the  stylus  over  the  lines  on  the 
drawing,  the  material  is  cut  to  the  same  contour  by 
the  cutting  burner.  The  burner  can  also  be  propelled 
by  a  small  electric  motor  by  having  a  suitable  connec- 
tion for  mechanical  drive  for  one  of  the  rollers. 


AUTOGENOUS  CUTTING  BURNERS  47 

Industrial  Applications.  —  In  ship  building  the  autog- 
enous cutting  process  is  employed  for  cutting  armor 
plate  and  for  cutting  openings  in  the  iron  plates  for 
bulkhead  doors  and  port  holes. 

For  such  work  as  is  continually  repeated  as,  for  ex- 
ample, the  cutting  of  port  holes,  openings  for  doors, 
manholes  for  steam  boilers,  etc.,  a  guide  rail  can  be 
used  to  advantage.  This  guide  rail  is  made  of  lead 
and  bent  to  the  form  of  the  opening  to  be  cut,  on  which 
rail  is  arranged  a  movable  carriage  having  a  suitable 
roller  guide  which  carries  the  burner. 

Such  device  is  often  used  where  the  burner  is  ar- 
ranged slanting  to  the  vertical  axis  of  the  plate.  By 
this  means,  slanting  cuts  are  obtained  which  are  so 
exact  that,  in  the  case  of  port  holes  or  similar  work, 
the  parts  cut  out  can  afterwards  be  used  as  doors. 

In  autogenous  cutting,  the  results  are  absolutely 
dependent  upon  the  stream  of  oxygen,  so  that  the  kind 
of  combustible  gas  used  for  the  preheating  flame  is 
relatively  unimportant  and,  in  such  choice,  economy 
is  the  sole  deciding  factor.  Of  all  the  known  gases 
acetylene  gives  the  hottest  flame  which  makes  it  par- 
ticularly adapted  for  the  purpose  of  autogenous 
cutting. 

With  correct  usage  of  a  properly  constructed  cutting 
burner  no  detrimental  change  of  material  at  the  cutting 
surface  takes  place. 

As  to  the  cost  of  the  autogenous  cutting  process 
different  tables  are  supplied  herewith  but  these  can  be 
regarded  as  only  approximately  correct. 


48 


AUTOGENOUS  WELDING  AND  CUTTING 


OXY-ACETYLENE    CUTTING 

GAS  CONSUMPTION  AND  TIME  REQUIRED 


Thickness  of 

Oxygen 

Acetylene 

Time 

Material. 

Consumption 

Consumption 

Occupied 

Mild  Steel 

Per  Metre  Cut 

Per  Metre  Cut 

Per  Metre  Cut 

5  m/m 

110  litre 

90  litre 

2  min.  50  sec. 

10     " 

140     " 

120     " 

4     fi     

15     " 

230    " 

180     " 

4     "     30  sec. 

20     " 

300     " 

250    " 

5     "     45    " 

30     " 

400    " 

320     " 

6     " 

50     " 

550    " 

400     " 

6     "     25  sec. 

75     " 

900    " 

650    " 

7    " 

100     " 

1400    " 

750    " 

8    "     

150     " 

2000     " 

900     " 

10     " 

OXYGEN-HYDROGEN  CUTTING 
GAS  CONSUMPTION  AND  TIME  REQUIRED 


Thickness  of 

Oxygen 

Hydrogen 

Time 

Material. 

Consumption 

Consumption 

Occupied 

Mild  Steel 

Per  Metre  Cut 

Per  Metre  Cut 

Per  Metre  Cut 

5  m/m 

108  litre 

90  litre 

5  min.  30  sec. 

10     " 

130    " 

100    " 

6     " 

15     " 

230    " 

110     " 

6     "     30  sec. 

20     " 

266     " 

110    " 

6     "     30    " 

30     " 

432     " 

110     " 

6     "     30    " 

40     " 

550    " 

110     " 

6     "     45    " 

50     " 

800    " 

180    " 

7     "     30    " 

75     " 

1033     " 

210    " 

8     " 

100     " 

2600    " 

380    " 

10     " 

150     " 

2800     " 

450     " 

10     "     

AUTOGENOUS  CUTTING  BURNERS 


49 


RESULT  OF  EXPERIMENTS  MADE  BY  TUCKER 
AT  BIRMINGHAM  (ENGLAND)  UNIVERSITY 


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2 

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273 

7.5 

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1.3 

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Good  cut 

3 

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Fairly  good 

4 

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68 

295 

9.8 

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1.7 

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5 

96.8 

66 

363 

11.8 

64 

2.1 

18.5 

101.9 

Very  rough 

6 

95.0 

67 

377 

11.6 

67 

2.1 

24.5 

98.0 

Not  clean  and  ragged 

7 

92.2 

69 

552 

15.0 

96 

2.6 

77.7 

150.0 

Very  ragged 

8 

88.2 

69 

615 

16.2 

107 

2.8 

98.1 

170.1 

Very  ragged  and  rough 

9 

87.3 

68 

660 

16.2 

117 

0.2 

116.6 

207.6 

Very  ragged  and  rough 

10 

83.3 

68 

855 

18.9 

152 

3.4 

181.4 

222.6 

Not  cut  through 

CHAPTER   VII 
AUTOGENOUS    WELDING    OF    IRON 

AUTOGENOUS  welding  is  a  process  for  fusing  together 
metallic  parts  and  is  applicable  for  all  metals  and  their 
alloys,  of  which  the  most  important  are  iron,  copper 
and  aluminium. 

In  dealing  with  the  characteristics  of  autogenous 
welding,  it  appears  advisable  to  discuss  the  more  im- 
portant metals,  a  knowledge  of  which  is  essential  for 
such  process. 

Iron.  —  Technical  iron  is  an  alloy  of  pure  iron  with 
other  elements,  the  most  important  of  which  is  carbon; 
and  the  different  properties  of  this  important  metal  are 
dependent  upon  the  carbon  content. 

Iron  with  less  than  .5%  carbon  is  called  malleable 
iron  or  mild  steel,  according  to  the  method  of  produc- 
tion. With  .5  to  1.5%  carbon  it  is  termed  steel;  and 
with  greater  carbon  content  it  is  known  as  cast  iron 
or  white  iron  (Figs.  43  to  51). 

Carbon  in  Molten  Iron.  —  Carbon  is  always  pres- 
ent in  molten  iron  similar  to  salt  dissolved  in  water, 
but  when  the  iron  becomes  solid,  the  diffused  carbon 
assumes  other  forms.  It  may  either  form  iron  carbide 
as,  for  instance,  in  pig  iron  or  mild  steel,  or  it  may  be 
transmuted  into  graphite  as  is  the  case  in  grey  cast 
iron.  It  may  continue  in  the  diffused  condition  within 
the  iron,  in  which  case  the  latter  forms  steel  or  white 
iron  according  to  its  contents  of  carbon. 

The  exact  transmutation  process  is  dependent  upon 

50 


AUTOGENOUS  WELDING  OF  IKON 


51 


FIG.  43.  —  Micro-photograph  of  mild  steel  bar. 
(Magnified  80  diameters) 


FIG.  44.  —  Micro-photograph  of  steel  bar  contain- 

ing 0.4  %  carbon. 
(Magnified  80  diameters) 


52  AUTOGENOUS  WELDING  AND  CUTTING 

the  other  materials  mixed  with  the  iron,  especially  the 
silicon  and  manganese.  Silicon  favors  the  formation 
of  graphite  in  cast  iron,  while  manganese  favors  the  for- 
mation of  steel  or  white  iron  according  to  its  percentage, 
or  the  form  of  the  carbon  content. 


FIG.  45.  —  Micro-photograph  of  steel  bar 

containing  about  0.75  %  carbon. 

(Magnified  80  diameters) 

The  fact  that  iron  can  assume  entirely  different 
physical  qualities  is  of  paramount  importance  in  the 
autogenous  welding  of  metals.  When  hydrogen  is 
employed  as  a  heating  agent  for  the  autogenous  weld- 
ing, a  decarbonization  of  the  iron  must  always  occur. 

With  the  employment  of  the  gases  for  heating, 
whose  products  of  combustion  contain  free  carbon,  the 
percentage  of  carbon  "in  the  iron  must  increase  during 
the  welding  operation. 

If  a  neutral  flame,  as  for  instance  a  properly  adjusted 
oxygen-acetylene  flame,  is  made  to  play  upon  the  molten 
iron,  the  percentage  of  carbon  in  the  metal  remains 
unchanged. 


AUTOGENOUS  WELDING  OF  IRON 


53 


FIG.  46.  —  Micro-photograph  of  steel  bar  contain- 
ing about  0.75  %  carbon. 
(Magnified  300  diameters) 


JTIG<  47,  —  Micro-photograph  of  steel  bar  contain- 
ing about  0.75  %  carbon  —  hardened. 
(Magnified  80  diameters) 


54  AUTOGENOUS  WELDING  AND  CUTTING 

The  molten  iron  however  is  still  capable  of  absorbing 
free  hydrogen,  which  gas  is  expelled  as  the  metal  be- 
comes rigid.  The  phenomenon  of  foaming  of  the  iron 
may  thus  occur  in  the  welding  seam:  the  iron  being 
divided  into  thin  films  surrounding  the  cavities  from 
which  the  gas  has  been  expelled. 

Effect  of  Excess  Carbon.  —  If  the  welding  flame 
contains  free  carbon,  the  latter  is  able  to  penetrate 
into  these  thin  films  and,  when  the  metallic  mass  cover- 
ing the  gas  bubbles  sinks  back  into  the  molten  material, 
the  welding  seam  becomes  enriched  with  carbon. 

The  seam  then  becomes  hard  and  brittle  and  in  this 
manner  the  welded  portion  of  wrought  iron  may  assume 
the  character  of  steel  or  even  that  of  cast  iron. 

The  molten  iron  has  also  the  quality  to  form  a 
compound  with  oxygen,  i.e.  to  be  burned,  and  as  the 
temperature  of  the  iron  is  increased  the  disposition 
to  combine  with  oxygen  is  also  increased.  At  the  same 
time,  the  chemical  product  of  the  combustion  of  the 
hydrogen,  superheated  steam,  is  set  free  with  each 
increase  in  temperature  and  above  a  certain  tempera- 
ture, the  oxygen  liberated  from  this  superheated  steam 
passes  into  the  molten  iron. 

Distinction  between  the  superheating  of  the  iron 
and  the  combustion  of  it,  is  made  entirely  according 
to  the  degree  of  the  compound  of  iron  and  oxygen. 
A  superheating  of  the  iron  is,  in  reality,  a  lesser  degree 
of  combustion. 

This  effect  of  free  oxygen  has  to  be.  considered  mainly 
in  such  gases  as  contain  free  oxygen,  free  hydrogen,  or 
free  carbon,  in  their  products  of  combustion. 

Similar  phenomenon  may  take  place  in  the  employ- 
ment of  acetylene,  if  this  gas,  in  the  course  of  its 
generation,  has  become  overheated  by  the  released 
reaction  heat.  The  gas  used  in  that  case  for  the  pur- 


AUTOGENOUS  WELDING  OF  IRON 


55 


FIG.  48.  —  Micro-photograph  of  nickel  steel  bar 

—  unmagnetic. 
(Magnified  300  diameters) 


FIG.  49. —  Micro-photograph  of  high-speed  steel  bar. 
(Magnified  80  diameters) 


56  AUTOGENOUS  WELDING  AND  CUTTING 

pose  of  welding  has  thus  partly  passed  into  the  poly- 
mere  compounds  of  acetylene. 

Contained  in  rolled  or  wrought  iron  are  flaws,  which 
were  not  eliminated  previous  to  the  ingot  becoming  rigid. 
In  the  process  of  rolling,  these  flaws  are  stretched  out  in 
the  same  direction  as  the  rolling  and  fibrous  layers  of 
iron  and  residues  are  formed  within  the  material. 

When  such  material  is  passing  into  the  molten  state, 
under  the  influence  of  the  welding  flame,  these  flaws 
contract  into  knotty  particles,  affecting  the  quality  of 
the  material  and  it  assumes  a  grainy,  in  place  of  a  fi- 
brous, character.  However,  by  a  suitable  mechanical^ 
after-treatment,  the  welding  place  can  be  given  the 
same  character  as  of  the  original  rolled  material. 

Pearlite.  —  It  has  been  previously  mentioned  that  the 
state  of  carbon  within  the  iron  determines  the  physical 
quality  of  the  latter.  In  a  compound  of  certain  per- 
centages of  carbon  and  iron,  the  particles  of  carbon 
assume  a  "  mother  of  pear^"  appearance,  which  par- 
ticles, sprinkled  among  the  mass  of  the  pure  iron,  are 
pearlite  or  cementite.  Pearlite  consists  of  an  iron  carbon 
alloy  with  from  .8%  to  .9%  of  carbon,  and  is  character- 
istic of  mild  steel. 

A  simple  method  of  determining  the  carbon  per- 
centage of  iron,  and  thereby  its  density,  has  been  given 
by  Baumann. 

Place  a  glass  plate  ruled  with  100  equal  squares, 
upon  the  photo  of  the  magnified  polished  surface  of 
the  iron  under  examination  and  the  carbon  percentage 
can  be  approximated  from  the  number  of  these  squares 
filled  with  pearlite. 

If  for  example  23  of  the  100  squares  are  filled  with 
pearlite,  the  calculation  is  as  follows: 


AUTOGENOUS  WELDING  OF  IRON 


57 


FIG.  50. —  Micro-photograph  of  cast  iron. 
(Magnified  300  diameters) 


FIG.  51.  —  Micro-photograph  of  white  iron. 
(Magnified  300  diameters) 


58  AUTOGENOUS  WELDING  AND  CUTTING 

It  has  also  been  mentioned  that  the  percentage  of 
silicon  and  manganese  is  the  determining  factor  of  the 
state  of  carbon  contained  in  the  iron.  Grey  cast  iron 
is  an  iron  of  high  carbon  percentage  in  which  the  car- 
bon content  is  in  the  form  of  graphite. 

Welding  of  Cast  Iron.  —  If  a  mass  of  grey  cast 
iron  is  to  be  treated  by  means  of  an  autogenous  weld- 
ing flame,  grey  cast  iron  of  a  high  carbon  percentage 
and  with  a  certain  higher  percentage  of  silicon  must 
be  employed  as  a  filling  material.  During  the  autog- 
enous welding  process,  a  part  of  the  silicon  contained 
in  the  casting  evaporates,  and  this  quantity  of  silicon 
must  therefore  be  replaced  by  the  filling  material. 

As  cast  iron  also  contains  manganese,  as  well  as 
silicon,  the  formation  of  white  iron  will  occur  in  the 


FIG.  52.  —  Etching  of  a  good  welding  seam. 

welding  place,  if  sufficient  silicon  evaporates  so  that 
the  manganese  predominates.  This  serves  as  an  ex- 
planation for  welding  seams  frequently  becoming  hard 
and  brittle  during  the  welding  of  grey  cast  iron. 

For  the  autogenous  welding  of  such  iron,  it  is  there- 
fore necessary  to  employ  as  filling  material  small  bars 
of  grey  cast  iron  of  high  percentage  of  carbon,  and  a 
still  higher  percentage  of  silicon. 

The  structure  of  the  grey  cast  iron  is  a  grainy  one 
and  in  order  to  lessen  the  influx  of  atmospheric  oxygen 
and  to  secure  a  better  structure  of  the  material,  it  is 
advisable  also  to  employ  one  of  the  common  fluxes, 
in  the  welding  of  such  castings. 


AUTOGENOUS  WELDING  OF  IRON  59 

After  the  place  to  be  welded  has  been  cut  away 
sufficiently  to  secure  good  results,  the  welding  flame 
is  applied  until  the  lowest  portion  of  the  metal  reaches 
a  molten  state.  The  heated  part  is  then  amply 
sprinkled  with  the  flux  and  the  welding  bar  is  also 
heated  and  plunged  into  the  molten  metal. 

Under  a  continuous  influence  of  the  welding  flame, 
the  molten  material  of  the  seam  is  stirred,  so  that  the 
filling  material  flows  off  and  fills  up  the  place  to  be 
welded. 

It  is  important  that  the  workman  should  carefully 
observe  the  flow  of  the  welding  seam  and  if  the  molten 
iron  is  blown  out  of  the  groove  by  the  flame,  the  work- 
man should  observe  whether  there  is  still  an  unfused 
portion  inside  the  welding  furrow,  the  characteristics 
of  such  imperfectness  being  the  appearance  of  film- 
like  layers  imbedded  within  the  molten  mass.  If  so, 
he  must  see  that  the  material  is  fused  in  this  place 
"also. 

If  the  welding  of  the  grey  cast  iron  has  been  properly 
executed,  the  structure   at 
the  welding  place  will   al- 
ways be  of  better  quality 
than  the  original  material. 

Welding  of  Cast  Steel.  — 
In  welding  cast  steel,  it 
must  be  taken  into  consid- 
eration that  this  is  a  mate- 
rial in  which  the  carbon 
percentage  is  between  that  FIG.  53.  —  Good  welds  after  hav- 

Of    mild    Steel    and    that    of          inS    been    subjected  to  severe 
,    .  T      .      ,  bending  test. 

grey  cast  iron.     It  is  best 

to  employ  small  cast  bars  of  the  same  metal,  as  filling 
material,  but  as  these  are  not  always  obtainable  Swedish 
soft  iron  may  be  used  in  conjunction  with  the  cast  bars. 


60 


AUTOGENOUS  WELDING  AND  CUTTING 


With  ordinary  care,  the  proper  percentage  of  carbon 
can  be  obtained  at  the  welding  place.  Weldings  of 
cast  steel  can  however  be  executed  with  good  results 
by  using  Swedish  soft-  iron  alone,  as  filling  material. 


FIG.  54.  —  Decarbonization  of  iron  in  a  welding  seam. 

Welding  of  Hard  Steel.  —  For  the  autogenous  weld- 
ing of  hard  steel  it  is  advantageous  to  employ  filling 
bars  with  a  high  percentage  of  manganese.  As  the 
elasticity  of  spring  steel  has  its  origin  in  the  process 
of  hardening,  if  it  is  desired  to  impart  physical  proper- 
ties to  the  welding  place  similar  to  those  of  the  rest  of 
the  material,  it  is  necessary  to  harden  the  material  of 
the  welding  place  in  the  usual  manner. 


FIG.  55. —  Traces  of  carbon  deposits  in  a  welding  seam. 

Welding  of  Wrought  Iron  or  Mild  Steel.  —  In 
welding  wrought  iron  or  mild  steel,  Swedish  soft  iron 
of  small  carbon  percentage  is  employed  as  filling 
material.  The  melting  point  of  such  a  material  is 
between  1500°  and  1600°  C.  (2732°  F.  to  2912°  F.). 
With  increasing  percentage  of  carbon  the  melting  point 
becomes  lower  and  it  sinks  as  low  as  1050°  C.  (1922° 
F.)  with  an  iron  of  such  high  carbon  content  as  grey 
cast  iron.  The  melting  point  of  iron  oxide  lies  at 
1350°  C.  (2462°  F.). 


AUTOGENOUS  WELDING  OF  IRON 


61 


In  the  autogenous  welding  of  mild  steel  and  wrought 
iron  the  melting  of  the  oxides,  if  any  exist,  must  be 
accomplished  simultaneously  with  the  melting  of  the 
metals.  The  melting  point  of  the  metal  is  sufficiently 


FIG.  56. —  Excessive  carbonization  in  a  welding  seam. 

high  to  destroy  the  oxides  and  as  the  metal  flows  to- 
gether directly  when  these  substances  are  worked  upon, 
there  is  no  need  of  a  flux  in  the  welding  of  these 
metals  (Figs.  52,  53,  54,  55,  56). 

In  grades  of  iron,  having  melting  points  lower  than 
that  of  the  iron  oxide,  the  fusing  of  this  oxide  can  not 
possibly  be  effected  as  the  temperature  of  the  latter  is  al- 
ways kept  down  by  that 
of  the  molten  metal.  In 
the  welding  of  such  mate- 
rials therefore,  it  is  neces- 
sary to  employ  a  welding 
powder,  or  flux,  which  is 
able  to  chemically  destroy 
the  existing  oxides.  The 
stirring  with  the  welding 
bar  during  the  welding 
operation  is  also  advisa- 
ble as  this  tends  toward  a  mechanical  destruction  of  the 
oxides.  (Fig.  57.) 

In  the  autogenous  welding  of  mild  steel  it  is  of 
great  importance  to  consider  the  state  in  which  the 
carbon  exists.  As  previously  mentioned  the  carbon 
always  exists  in  a  fluid  condition  in  molten  iron  and  it 


FIG.  57.  —  Method  of  stirring  the 
molten  metal  with  the  filling  bar 
during  the  welding  operation  to 
destroy  the  films  of  oxide. 


62  AUTOGENOUS  WELDING  AND  CUTTING 

is  only  when  the  metal  becomes  rigid  that  its  condi- 
tion changes.  In  the  case  of  mild  steel  the  carbon 
content  consists  of  pearlite. 

Martinsite.  —  It  is  well  known  from  the  hardening 
treatment  that  by  a  process  of  sudden  cooling  and 
quenching,  certain  states  of  the  metal  can  be  lastingly 
obtained  which  otherwise  only  exist  at  higher  tempera- 
tures. In  the  autogenous  welding  of  mild  steel  there  is 
always  the  danger  that,  in  consequence  of  a  rapid  cool- 
ing, a  liquid  form  of  the  carbon  is  retained  in  the  iron, 
so  that  the  welding  seam  assumes  the  character  of  steel. 
It  is  then  possible  that  Martinsite  will  exist  in  place  of 
pearlite. 

Martinsite  is  a  substance  which  has  the  same  per- 
centage of  carbon  as  pearlite,  but  differs  from  the  latter 
in  its  great  hardness.  If  martinsite  is  produced,  the 
welding  seam  of  mild  steel  becomes  hard  and  brittle 
and,  therefore  such  changes  of  the  material  should 
be  avoided. 

Welding  of  Cast  Steel  and  Wrought  Iron.  —  In 
the  'welding  of  cast  steel  and  wrought  iron  or  similar 
combination  which  is  frequently  done  in  the  manu- 
facture of  certain  articles,  the  peculiarities  of  each 
metal  must  be  carefully  considered.  In  the  construc- 
tion of  motor  valves,  for  example,  the  spindle  is  made 
of  wrought  iron  and  the  disk  of  cast  steel,  owing  to 
these  parts  being  subjected  to  different  stresses.  The 
union  is  effected  by  means  of  the  autogenous  welding 
flame  in  the  regular  manner. 


CHAPTER   VIII 
REPAIRS    OF    GREY    CAST    IRON 

A  VERY  wide  field  for  autogenous  welding  is  the 
repair  of  broken  cast  iron  pieces.  As  previously 
mentioned,  grey  cast  iron  is  an  alloy  with  a  high  per- 
centage of  carbon  and  a  still  higher  percentage  of 
silicon  and  the  presence  of  the  latter  causes  the  carbon 
to  exist  in  the  form  of  graphite. 

Formation  of  White  Iron.  —  Silicon  has  so  low  a 
boiling  point  that  under  the  influence  of  a  welding 
flame  it  evaporates  and  without  special  precaution, 
the  percentage  of  silicon  contained  would  be  consider- 
ably reduced  during  the  welding  of  grey  cast  iron. 
This  would  result  in  the  carbon  content  assuming  an- 
other form  and  white  iron  would  exist  in  that  portion 
of  the  material  influenced  by  the  welding  flame.  Owing 
to  the  characteristics  of  white  iron,  the  welding  seam 
would  become  hard  and  brittle. 

This  phenomenon  must  be  avoided  and  its  preven- 
tion is  of  such  importance  that  the  author  repeats 
its  mention  here  again.  The  details  of  the  correct 
treatment  are  given  in  the  preceding  chapter. 

Presence  of  Tensions.  —  In  grey  iron  castings,  high 
tensions  exist  in  the  individual  portions,  due  to  the 
unequal  cooling  of  the  mass,  during  its  manufacture 
and  these  tensions  usually  cause  cracks  if  other  forces 
later  on  influence  the  substance. 

Such  latent  tensions  exist  in  the  spokes  of  wheels  at 
the  point  where  the  relatively  greater  mass  of  the  rim 

63 


64 


AUTOGENOUS  WELDING  AND  CUTTING 


joins  the  thinner  mass  of  the  spokes.  Attempts  to 
weld  such  spokes,  without  the  necessary  preparation, 
would  result  in  new  cracks  when  the  cooling  down  takes 
place. 

The  proper  method  of  execution  is  first  to  heat  the 
rim  so  that  it  will  expand  and  thus  enlarge  the  fissure 

in  the  spoke.  While  the 
casting  is  in  such  heated 
state,  the  welding  of  the 
crack  should  be  completed 
in  the  regular  prescribed 
manner  of  welding  such 
material  (Fig.  58). 

Value  of  Preheating.  — 
In  this  manner,  the 
stresses,  which  occur  when 
the  piece  under  treatment 
gets  cold  and  shrinks,  may 
be  avoided.  The  pre-heat- 
ing  of  the  material  trans- 
forms such  tensions  into 
pressure  strains  which  are 
much  more  favourable  to  the  cast  material. 

The  co-efficient  of  tension  for  cast  iron  is  0.014%; 
i.e.,  for  every  increase  of  100°  C.  in  temperature,  there 
is  an  increase  in  the  mass  of  the  object  equal  to  1.4 
m/m  for  each  metre  length.  As  the  melting  point  of 
cast  iron  is  1050°  C.  it  is  evident  that  the  total  expan- 
sion of  the  material  from  freezing  point  (0°  C.)  to  the 
molten  state  is  1.4  x  10.5  or  14.7  m/m  for  each  metre 
length. 

Expansion.  —  The  conductivity  of  cast  iron  is  com- 
paratively low  and  as  the  stretching  is  distributed  over 
the  material  within  reach  of  the  heating,  it  may  be 
assumed  that  this  tension  value  of  14.7  has  to  be  di- 


FIG.  58. —  Locomotive  drive  wheel 
with  cracks  in  spokes  repaired  by 
autogenous  welding. 


REPAIRS  OF  GREY  CAST  IRON  65 

vided  by  2  in  order  to  obtain  an  approximately  correct 
figure.  Therefore  for  each  metre  length  (39.37  inches) 
of  the  mass  heated,  by  a  portion  being  raised  to  the 
melting  point,  a  stretching  of  7.35  m/m  (19/64  inches) 
results,  i.e.  about  3/32  inches  for  each  foot  in  length, 
and  in  the  portions  outside  but  rigidly  connected  to 
the  welding  area  a  crushing  of  the  material  for  about 
5  m/m  occurs  during  the  welding  operation. 


FIG.  59  FIG.  60 

FIGS.  59—60. —  Broken  motor  cylinder  and  same  after  having 
been  repaired  by  autogenous  welding. 

The  material  which  is  thus  compressed  during  the 
welding  is  also  subjected  to  as  equally  great  tension  due 
to  shrinkage  of  mass  when  cooling.  This  stretching 
in  cast  iron  objects  exists  in  two  dimensions  in  a 
plane  and  in  three  dimensions  in  a  solid. 

Prevention  of  Cracks.  —  To  prevent  subsequent  forma- 
tion of  fissures,  it  is  absolutely  necessary  to  previously 
heat  all  material  affected  by  the  expansion  or,  better  still, 
to  heat  the  whole  casting  equally  to  a  dull  red,  except 
where  a  loose  piece  is  to  be  welded  on  one  end  only. 

The  whole  mass  in  this  manner  undergoes  such  a 
universal  stretching  that  the  local  surplus  of  heat  oc- 
casioned by  the  welding  operation  has  no  appreciable 
effect  in  expansion. 


66 


AUTOGENOUS  WELDING  AND  CUTTING 


Repairing  Complex  Castings.  —  For  the  welding  of 
a  complex  casting,  as  for  example,  a  motor  car  cylinder, 
it  is  advisable  to  bring  the  material  into  a  dull  red 
state  by  a  slow  fire,  in  a  suitable  furnace,  so  that  the 
heat  penetrates  the  whole  mass. 

While  the  casting  is  in  such  heated  state  it  should 
be  removed  from  the  furnace  and  the  fissure  welded 


FIG.  61  FIG.  62 

FIGS.  61-62.  —  Broken  machine  support  and  same  after  having  been 
repaired  by  autogenous  welding. 

as  quickly  as  possible  and  then  be  immediately  returned 
to  the  furnace  so  that  it  can  be  again  heated  as  pre- 
viously, before  being  finally  allowed  to  cool.  It  may  be 
safely  expected  in  the  welding  operations  so  executed 
that  no  tensions  or  formation  of  new  fissures  will  occur 
in  the  cooling  down  process  (Figs.  59,  60). 

Repairing  Large  Castings.  —  When  repairing  broken 
corners  of  engine  bases  and  machinery  beds  or  similar 


REPAIRS  OF  GREY  CAST  IRON  67 

work,  the  material  in  the  welding  area  should  be  suit- 
ably prepared  and  the  welding  started  in  the  middle 
part  of  the  fracture  and  continued  to  either  end. 
When  one  half  of  the  welding  has  been  completed  the 
whole  mass  should  be  allowed  to  get  cold  before  the 
remainder  of  the  work  is  executed,  for  if  this  is  not  done 
the  appearance  of  a  new  crack  may  be  expected  during 
the  second  part  of  the  operation  (Figs.  61,  62). 

In  this  treatise  only  general  points  of  view  can  be 
given,  but  a  welder  will  always  be  able  with  the  as- 
sistance of  these  data,  to  determine  whether  the  autog- 
enous method  can  be  employed  and  how  such  repairs 
should  be  executed. 


CHAPTER   IX 
WELDING    OF    SHEET    IRON 

THE  method  employed  in  the  welding  of  sheets  of 
mild  steel  varies  according  to  the  nature  and  thickness 
of  the  material  worked  upon. 

In  the  welding  of  thin  sheets  the  seam  is  exposed  to 
different  temperatures  of  the  flame  and,  in  consequence 
of  this,  a  slow  drop  in  temperature  occurs  immediately 
upon  the  metal  becoming  rigid,  so  there  is  no  danger  of 
the  metal  in  the  welding  seam  becoming  brittle. 

The  welding  of  very  thin  sheets  such  as  a  thickness 
of  \  m/m  (.02  inches)  can  be  facilitated  by  turning 

up  the  edges  of  the  sheets  so  as 
to  leave  a  small  flange  of  per- 
haps 3  m/m  (.12  inches)  in  height 
at  the  place  of  union  (Fig.  63). 
FIG.  63.—  Thin  sheets  flanged  The  application  of  the  welding 

preparatory  for  welding.  flame    ^    ^^    flangeg    simulta. 

neously  serves  to  fuse  one  with  another  effectively  join- 
ing the  two  sheets  and  in  this  manner  the  flanges,  being 
melted  down,  replace  the  bar  of  filling  material  used  in 
heavier  sheets. 

This  method  of  working  is  used  in  all  cases  where 
the  manufacture  of  stamped  work  is  accomplished  by 
uniting  sections  of  sheet  metal,  previously  cut  for 
the  purpose.  Also,  in  the  manufacture  of  cylindrical 
sections,  it  is  usual  to  leave  a  flange  or  rib,  where  the 
sheets  are  to  be  joined  and  then  to  melt  down  this 
rib  on  the  cylindrical  surface. 

68 


WELDING  OP  SHEET  IRON 


69 


c 


In  such  work  it  is  advisable  to  tack  the  pieces  to- 
gether by  welding  the  edges  of  the  flange  at  intervals 
of  about  100  m/m  (4  inches)  before  melting  down 
the  whole  flange.  In  the  tacking  process,  the  flanges 
are  held  together  with  clamps,  in  order  to  secure  the 
correct  relative  position  of  the  sheets. 

Flanging  of  Sheets.  —  In  the  manufacture  of  stamped 
sheet-steel  articles,  the  flange  is  formed  during  the 
stamping  process. 

This  method  of  flanging  sheets  at  the  welding  place 
is  extensively  employed  in  the 
manufacture  of  thin  sheet  metal 
articles  (Fig.  64)  and  also  in  the 
construction  of  large  vessels 
where  thicker  sheets  are  used. 

The  latter  are  usually  vertical 
cylindrical  tanks  built  up  of 
sheets  of  varying  thickness  ac- 
cording to  the  different  service 
conditions.  As  the  pressure  of 
the  liquid  contents  of  a  vessel 
varies  at  different  heights,  sheets 
are  employed  according  to  re-  FIQ  64 
quirements  and  become  thinner 
upwards  from  the  bottom. 

If  the  edges  of  the  sheets  are 
turned  at  right  angles  for  about  25  m/m  (1  inch),  the 
welding  can  be  made  upon  the  outer  edges  of  the  rib  itself. 
In  this  case  the  double  layer  of  sheet  remains  as  a  sup- 
port which  serves  to  give  the  whole  vessel  greater  strength 
and  power  of  resistance. 

If  the  thickness  of  the  sheet  exceeds  3  m/m  (J  inch), 
it  becomes  necessary  to  bevel  the  edges,  so  as  to  allow 
a  perfect  welding  through  the  whole  thickness  of  the 
material.  In  this  case  however,  it  is  necessary  to  em- 


Sectional  views  of 
stampings  of  thin  sheet 
metal  with  flanges  for 
welding  purposes. 


70  AUTOGENOUS  WELDING  AND  CUTTING 

ploy  other  metal  for  supplying  the  material  lacking  to  fill 
up  the  welding  groove.  For  such  purposes,  it  is  usual 
to  employ  a  soft  Swedish  charcoal  iron  drawn  into  wire. 

In  welding  thin  sheets,  it  is  advisable  to  keep  the 
filling  wire  in  the  direction  of  the  welding  seam  so  that 
it  is  possible  to  melt  it  directly  into  the  groove.  For 
this  process  a  certain  experience  is  required  but,  if 
one  is  not  too  easily  discouraged,  he  will  soon  acquire 
the  proper  way  of  doing  this  kind  of  work. 

Welding  of  Very  Thin  Sheets.  —  If  still  thinner 
pieces  of  sheet  are  to  be  united,  the  edges  are  usually 


FIG.  65. —  Double  hook  FIG.  66. —  Diagram  showing  appli- 

used  in    welding    of  cation  of  heat-absorbing  blocks 

very  thin  sheets.  to  prevent  overheating   in    the 

welding  of  very  thin  sheets. 

hooked  together  by  a  hemming  operation  (Fig.  65). 
Before  applying  the  welding  flame  the  hem  is  super- 
imposed upon  a  block  of  material  which  possesses  great 
heat  conductivity  and  sufficiently  large  to  be  effective. 

As  will  be  seen  in  the  accompanying  illustration  (Fig. 
66),  the  parts  to  be  joined  lie  in  a  groove  in  the  block 
and,  as  the  material  is  in  several  layers,  the  welding 
can  be  carried  out  without  danger  of  burning  the  metal. 

In  performing  this  work  the  torch  should  be  held  at 
as  sharp  an  angle  as  possible  as,  in  that  manner,  a  larger 
thickness  of  material  is  placed  in  the  direction  of  the 
axis  of  the  welding  flame.  In  such  operations,  it  is 
of  advantage  to  make  the  heated  areas  of  the  material 
as  small  as  possible  as  this  prevents  the  material  be- 
coming warped  and  distorted. 

Position  of  Welding  Torch.  —  As  the  sheets  become 
thicker  the  position  of  the  burner  must  be  more  ver- 


WELDING  OF  SHEET  IRON 


71 


tical  to  the  work.  The  correct  adjustment  of  the  flame 
is  of  great  importance  for  these  operations  and  great 
care  should  be  taken  to  insure  that  the  flame  has  neither 
an  excess  of  oxygen  nor  of  acetylene.  It  is  also  impor- 
tant that  the  material  is  struck  by  the  flame  in  welding 
so  that  the  inner  cone  of  the  flame  is  from  3  to  5  m/m 
(|  to  3/16  inches)  from  the  sheet. 

In  the  welding  of  sheets  of  from  2  to  3  m/m  in  thick- 
ness, the  burner  has  to  be  so  placed  that  it  meets  the 
welding  seam  approximately  under  an  angle  of  45°. 


FIG.  67. —  Butting  together 
the  edges  of  sheets  for 
welding  purposes.  This 
method  is  satisfactory  for 
sheets  up  to  3/32  inch  in 
thickness. 


FIG.  68.  —  Bevelling  the 
edges  of  thick  sheets  for 
welding  purposes.  This 
method  should  be  used  on 
sheets  having  a  thickness 
of  i  inch  or  over. 


Often  in  industrial  work,  a  thorough  welding  of  the 
seam  is  obtained  in  sheets  up  to  a  thickness  of  5  m/m 
(3/16  inches)  without  the  previous  bevelling  of  the 
edges  of  the  sheets.  This  however  is  a  matter  of  in- 
dividual ability  and  those  who  are  not  experienced 
in  the  autogenous  welding  process  , 

should  always  bevel  the  edges  of  the 
sheets,  if  they  are  more  than  3  m/m 
(Figs.  67,  68,  69). 

Unless  thick  sheets  are  bevelled,    FIG.  69.  -  Double  bev- 

.  '         ellmg  of  edges  of  very 

the  union,  in  the  groove  of  the  weld-       thick  sheets  (f  inch 
ing   seam,    is    not   reliable  and   the       or  over)  for  welding 

i  u-    u  i      •    •       j          purposes. 

places  which  are  not  properly  joined 
act  as  a  fissure  which  permit  the  easy  breaking  of  the  weld. 
Failures  of  Welds.  —  In  different  cases,  such  imper- 
fect welding  has  been  the  cause  of  the  rupture  of  ves- 


72  AUTOGENOUS  WELDING  AND  CUTTING 

sels  subjected  to  pressure  and  thence  deductions  were 
drawn  unfavourable  to  the  fitness  of  autogenous  weld- 
ing in  general.  But  this  was  of  course  perfectly  errone- 
ous, as  in  these  cases,  the  conclusion  can  only  be  drawn 
as  to  the  imperfect  way  the  process  was  handled  (Figs. 
70,  71,  72,  73,  74,  75,  76,  77). 


FIG.  70.  —  Evidence  of  superheating  of  a  welding  seam. 

In  the  case  of  fire,  or  ordinary  blacksmith  welding, 
such  imperfect  welds  will  occur  if  the  process  is  unskil- 
fully handled,  and  this  will  frequently  be  the  case  where 
thick  materials  are  welded  in  a  fire. 

In  welding  thick  sheets  of  mild  steel,  the  heat  stored, 
in  the  adjoining  parts  of  the  sheet,  is  sufficient  to  pre- 
vent the  welding  seam  from  cooling  down  too  rapidly 
and  thus  becoming  hard  or  brittle. 


FIG.  71. —  Excessive  superheating  in  lower  part  of  a  welding  seam. 

Existence  of  Oxides.  —  In  the  slow  cooling  of  the 
welding  seam,  where  films  of  the  oxide  remain  in 
the  mass,  there  is  a  danger  that  the  temperature  of 
the  material  gets  below  the  melting  point  of  these 
oxides  before  the  latter  are  destroyed.  These  oxides, 


WELDING  OF  SHEET  IRON  73 

when  included  in  the  material,  arrange  themselves  across 
the  direction  of  the  rolling  of  the  metal  and  thus  en- 
danger considerably  the  strength  of  the  metal  in  the 
weld. 


FIG.  72. —  Evidence  of  superheating  of  a  welding  seam  and  unwelded 
spots  (a.  a.). 

In  order  to  avoid  such  a  condition,  the  following 
method  should  be  employed  in  the  welding  of  sheets 
that  are  later  on  to  be  subjected  to  heavy  pressure. 
Before  the  welding  operation  is  commenced,  the 
material  adjoining  the  parts  to  be  joined  should  be 
heated  up  to  red  heat,  by  the  welding  flame,  thereby 
surrounding  the  place  of  union  with  a  zone  of  heated 
metal. 


FIG.  73. —  Superheated  and  carbonized  welding  seam  containing  for- 
eign matter  (a.  b.  c.). 

As  this  heat  is  therefore  conducted  to  the  parts 
to  be  welded  during  the  operation,  it  is  evident  that 
there  is  an  increase  of  heat  at  the  weld  rather  than  a 
loss  of  heat  which  would  occur  otherwise.  The  weld- 
ing can  then  be  effected  with  comparative  rapidity 


74  AUTOGENOUS  WELDING  AND  CUTTING 

as  the  material  welded  remains  under  the  influence 
of  the  welding  flame  a  much  shorter  time  and  the 
danger  of  the  temperature  of  the  metal  falling  below  the 
melting  point  of  the  oxides  is  avoided. 


FIG.  74. —  Imperfect,  superheated,  and  carbonized  welding  seam. 

Magnetic  Properties  of  Iron.  —  Iron  has  the  pecu- 
liarity to  lose  its  magnetism  at  a  temperature  close  to 
700°  C.  or  1300°  F. 

In  the  welding  of  heavy  sheets  which  are  afterwards 
subject  to  exacting  conditions,  the  welded  parts  should 
be  heated  by  the  flame  after  the  welding  operation  is 
completed.  Such  subsequent  heating  has  the  effect 
that  the  structure  of  the  material  receives  an  im- 
portant refinement. 


FIG.  75. —  Fracture  in  a  welding  seam  as  the  result  of  improper  welding. 

In  such  a  procedure  it  is  necessary  that  between 
the  heating  immediately  previous  to  the  welding  and 
the  exposure  to  the  flame  subsequent  to  the  operation 
a  complete  cooling  down  to  a  temperature  not  to 
exceed  20°  C.  (98°  F.)  occurs  for  effective  results,  The 


WELDING  OF  SHEET  IRON  75 

second    heating   should    raise   the   temperature    of   the 
welded  part  to  not  less  than  700°  C.  or  1292°  F. 


FIG.  76. —  Unwelded  place  in  seam  (a— a)  in  consequence  of  improper 
holding  of  the  burner. 

Value  of  Reheating.  —  For  example,  in  two  welds 
made  in  the  same  sheet,  with  equal  care  and  under 
similar  conditions,  the  difference  in  results  may  be 
easily  recognised  if  one  is  allowed  to  cool  down  com- 
pletely and  the  other  is  reheated  by  the  flame  after 
the  temperature  lowers  to  approximately  20°  C.  or 
98°  F. 

Upon  breaking  the  two  welding  seams,  it  will  be 
found  that  the  fracture  of  material  of  the  welding 
seam,  which  has  not  been  heated  the  second  time,  is 
composed  of  coarse  crystals,  while  the  fracture  of  the 


FIG.  77. —  Example  of  bad  welding. 

reheated  weld  will  consist  of  fine  grains  with  fibres 
running  through  the  metal.  This  change  of  material 
takes  place  at  the  temperature  at  which  the  iron  loses 
its  magnetism  and  it  would  mean  a  loss  of  energy  and 
heat  if  the  second  heat  exposure  is  continued  to  pro- 
duce a  higher  temperature  than  is  absolutely  necessary. 


76 


AUTOGENOUS  WELDING  AND  CUTTING 


A  process  has,  however,  been  developed  which  makes 
it  possible  to  prevent  a  superfluous  heating  of  material 
during  the  second  exposure  and  to  prevent  the  loss  of 
heat  and  time  consequent  upon  it. 

Test  of  Magnetism.  —  By  taking  a  common  horse- 
shoe magnet  (Fig.  78),  the  testing  of  the  magnetic 
properties  of  the  welding  spot  during 
the  second  exposure  can  be  accom- 
plished. As  soon  as  the  magnetism 
disappears,  the  heating  of  the  welded 
area  should  cease. 

Such  second  heating  of  the  welding 
seams  should  be  carefully  done  in  all 
sheets  which  are  later  on  subjected  to 
pressures,  especially  in  the  repairing 
and  manufacturing  of  steam  boilers. 

Puddling  Process.  — In  welding 
heavy  material  which  is  later  on  sub- 
the  magnetic  prop-    jected  to  exacting  conditions,  it  is  nec- 
£0ts  essary  that  the  welding  seam  during 

its  creation  be  subjected  to  a  process 
of  refining  which  corresponds  to  the  process  known  in 
steel  works  as  "  puddling." 

After  due  preparatory  heating,  the  workman  starts 
welding  in  the  bottom  of  the  V  shaped  groove  formed 
by  the  two  bevelled  edges,  but  he  must  be  sure  that 
the  welding  flow  shows  a  smoothness  in  the  bath. 
Contents  of  oxide  betray  their  presence  by  a  somewhat 
darker  condition  in  the  fused  material  which  may  be 
noticed  by  a  trained  eye.  When  the  welder  notices 
a  darker  spot  in  the  molten  material  he  should  turn 
the  effective  part  of  the  welding  flame  upon  it  so  that 
the  oxide  may  be  reduced  to  metallic  iron. 

After  the  welder  has  built  up  the  lowest  part  of 
the  welding  trough  to  a  thickness  of  5  m/m  (3/16 


WELDING  OF  SHEET  IRON 


77 


inches),  he  starts  gently  hammering  the  molten  metal 
by  a  small  hammer  with  piens  of  such  shape  to  enable 
the  metal  to  be  reached  at  the  base  of  the  groove 
(Fig.  79).  The  playing  of  the  welding  flame  simul- 
taneously with  the  hammering  is 
continued  during  the  building  up  of 
the  welding  seam  to  its  full  thick- 
ness and  it  corresponds  to  a  kind  of 
puddling.  During  this  operation  it 
is  necessary  to  cool  the  head  of  the 
hammer  from  time  to  time,  by  im- 
mersion in  water,  and  thus  prevent 
its  destruction  by  the  flame. 

Improvement  in  Material.  —  By 
these  means,  densification  of  the 
material  and  an  increased  strength 
is  obtained.  After  the  whole  weld- 
ing groove  has  been  built  up  with 
filling  material,  it  is  common  prac- 
tice to  effect  a  smoothening  of  the 
surface  by  using  a  small  hammer, 
with  a  contact  of  not  to  exceed  8  m/m,  which  hammer 
may  also  be  plunged  in  water  for  cooling. 

It  is  essential  to  successful  operation  that  this  kind 
of  hammering  is  done  while  the  welding  seam  is  at  a 
bright  red  heat.  If  the  welding  seam  is  worked  upon, 
while  at  a  temperature  below  the  red  glow  of  the 
material,  or  with  a  larger  hammer,  internal  fractures 
of  the  metal  occur  which  damage  the  welding  seam. 
Upon  the  right  kind  of  hammering,  the  quality  of  the 
welding  seam  depends  to  a  large  extent  (Figs.  80,  81). 

Use  of  Two  Welding  Torches.  —  In  the  case  of  very 
thick  sheets,  the  welding  may  be  performed  by  welding 
flames  on  both  sides  of  the  sheet  operated  simul- 
taneously, but  great  care  and  strict  observance  of  the 


FIG.  79.  —  Puddling 
hammer. 


78 


AUTOGENOUS  WELDING  AND  CUTTING 


above  mentioned  rules  is  necessary  for  satisfactory 
results.  The  edges  of  the  sheets  must  be  bevelled 
upon  both  sides  and  the  welding  will  be  performed 
to  the  best  advantage  with  the  sheets  in  a  vertical  or 
horizontal  position  (Fig.  82). 


FIG.  80. —  Photograph  showing  disappearance  of  burned  par- 
ticles which  had  been  contained  in  the  welding  seam. 

While  there  is  always  a  mass  of  molten  metal  which 
would  flow  back  into  the  groove  formed,  when  the 
welding  flame  is  played  from  above,  a  dropping  away 
of  the  molten  iron  will  occur  in  vertical  welding  and  in 
consequence  great  difficulties  arise  in  such  work. 


FIG.  81. —  Photograph  showing  disappearance  of  burned  particles 
which  had  been  contained  in  a  double-sided  welding  seam. 

Vertical  and  Overhead  Welding.  —  In  executing 
vertical  welding,  or  when  a  workman,  tying  on  his 
back,  has  to  weld  the  sheet  from  underneath,  the  drop- 
ping away  of  the  molten  iron  can  be  prevented  in  the 
following  manner: 

The  area  adjoining  the  welding  place  is  heated  until 
the  metal  is  white  hot  and,  when  this  condition  is 
secured,  the  flame  is  played  upon  the  weld  while  simul- 
taneously the  filling  wire  is  inserted  in  the  welding 
groove.  At  such  a  high  temperature,  the  adhesion 
of  the  material  influences  the  molten  portion  of  the 
filling  wire  so  that  the  latter  spreads  itself  out  upon* 


WELDING  OF  SHEET  IRON 


79 


the  surface  of  the  material,  in  homogeneous  compound, 
and  thereby  the  formation  of  drops  is  avoided. 


FIG.  82. —  Double  weld  in  a  very  thick  mild  steel  sheet. 

It  is  in  this  manner  that  experienced  welders  are  able 
to  execute,  with  equal  ease,  the  repairs  of  boilers  in 
any  and  every  position  that  is  required. 


CHAPTER  X 
MANUFACTURE    AND   REPAIRS    OF    BOILERS 

THE  autogenous  welding  process  is  variously  applied 
to  the  repairs  of  boilers.  In  such  work  the  strains 
imposed  upon  the  places  to  be  repaired  have  to  be 
carefully  considered,  since,  under  service  conditions, 
the  material  of  a  boiler  is  subjected  to  constant  alter- 
ations resulting  from  changes  of  temperature  and 
position. 

Effect  of  Temperature  Variations.  —  The  structural 
appearance  of  mild  steel  sheets  varies  with  the  temper- 
ature of  the  metal.  The  same  material,  which  is  coarse 
grained  in  a  cold  state,  will  be  finely  grained  and  fibrous 
at  the  usual  service  temperature  of  modern  boilers 
of  200°  C.  to  300°  C.  (392°  F.  to  572°  F.).  This  is  the 
reason  why  the  power  of  resistance  in  the  material  of 
boilers  is  always  greater  at  certain  higher  temperatures. 

FaMures  of  boilers  often  result  from  the  usual  manner 
of  joining  of  overlapping  sheets  which  consists  of  pier- 
cing the  two  sheets  and  inserting  rivets.  In  the  fur- 
nace, for  example,  the  sheet  exposed  to  the  flame  acts 
as  a  receiver  of  heat,  and  the  second  sheet  as  a  con- 
ductor of  heat,  the  double  thickness  of  sheet  somewhat 
retarding  the  passage  of  heat  to  the  water. 

Causes  of  Failures.  —  If  the  one  sheet  is  much 
heated  by  the  flame  it  must  expand  to  a  greater  ex- 
tent than  the  other  sheet,  which  is  kept  nearly  of 
the  same  temperature  as  the  water  around  it.  In 
a  cold  state,  the  connecting  rivets  will  stand  parallel 

80 


MANUFACTURE  AND  REPAIRS  OF  BOILERS        81 

to  each  other,  but,  when  the  two  sheets  are  heated 
to  unequal  temperatures,  a  straining  of  the  rivets  will 
occur,  since  they  pass  from  a  parallel  to  a  converging 
position. 

Further  while  the  boiler  is  in  service  the  inner  surface 
of  the  fire  tubes  will  remain  of  nearly  equal  tempera- 
ture so  long  as  the  fire  door  is  kept  closed,  but  each 
time  the  door  is  opened  a  cold  air  current  will  enter 
the  fire  tube  and  cause  the  material  to  cool  down  and 
shrink.  These  fluctuations  of  temperature  impose  con- 
siderable strains  upon  the  material,  but  particularly 
upon  the  rivets. 

It  is  apparent  therefore  that  the  rivet  holes  must 
eventually  become  oval  shaped  and  permit  the  water 
to  enter  the  unoccupied  space  causing  a  corrosion  of 
the  material,  which  defects  finally  assume  such  pro- 
portions that  the  boiler  has  to  be  taken  out  of  service. 

Change  of  Methods.  —  As  other  methods  of  join- 
ing sheets  were  unknown,  in  the  beginning  of  the 
boiler  making  industry,  it  was  necessary  to  employ 
rivetting  notwithstanding  these  defects.  The  process 
has  been  so  developed  and  perfected  that  it  will  now 
be  rather  difficult,  if  at  all  possible,  to  replace  the 
rivetting  of  boilers  by  autogenous  welding. 

When  a  method  of  examining  an  autogenous  welding 
seam  has  been  devised  by  which  the  quality  of  the 
seam  can  be  reliably  determined  without  injuring  the 
metal,  it  is  probable  that  the  welding  process  will  be 
more  generally  employed  in  the  construction  of  boilers. 

For  the  present,  however,  such  welding  method 
furnishes  an  economical  and  reliable  means  of  repairing 
the  corrosions  and  fractures  which  occur  in  boilers, 
during  their  use. 

To  repair  worn  rivet  holes,  the  adjacent  rivets  must 
be  removed  for  a  distance  of  from  300  m/m  to  500 


82  AUTOGENOUS  WELDING  AND  CUTTING 

m/m  (12  to  20  inches)  in  order  to  permit  the  material 
to  stretch  freely  during  the  local  heating  caused  by 
the  welding  and  also  to  permit  a  free  shrinking  during 
the  cooling  down  of  the  metal. 

Welding  of  Cracks.  —  The  same  applies  to  the 
welding  of  cracks.  Cracks  in  boiler  sheets  are  usually 
caused  by  bending  strains  on  the  material  consequent 
upon  alternate  internal  pressures,  and  they  are  quite 
common  in  the  places  where  such  strains  exist. 

When  a  crack  is  to  be  welded  autogenously  suitable 
preparation  must  be  made  to  prevent  the  expansion 
of  the  adjoining  portions  of  the  sheet  toward  the  weld- 
ing seam.  As  the  metal  has  to  be  transformed  into 
a  plastic  and  liquid  state,  it  is  evident  that  such  ex- 
pansion would  result  in  the  material  of  the  welding 
seam  being  compressed  and  forced  out  during  the 
operation. 

Crack  welding  executed  in  this  manner  would  cause, 
during  the  cooling  period,  a  shrinkage  of  the  material 
in  direct  relation  to  the  fall  of  temperature.  The 
welded  place  would  be  compelled  to  stand  such  an 
extraordinarily  strong  pull  as  to  be  torn  open  again. 

Avoidance  of  Strains.  —  It  is  therefore  very  neces- 
sary that  subsequent  strains  in  the  welding  seam  during 
the  cooling  down  process  be  avoided.  In  welding  a 
crack  in  a  boiler  sheet  it  is  advisable,  after  the  nec- 
essary cutting  away  of  the  material,  to  drive  a  chisel 
or  other  wedge  into  the  fissure  to  further  expand  it,  in 
which  case  tension  will  exist  in  the  adj  oining  portions. 

If,  while  such  tension  exists,  the  welding  is  completed 
to  the  place  where  the  chisel  is  inserted,  a  pressure  on 
the  adjoining  material  must  result,  instead  of  a  pull, 
when  the  chisel  is  removed.  It  is  then  possible  to  en- 
tirely weld  up  the  place  of  the  fissure  in  which  the  chisel 
was  placed  without  fear  of  another  fissure  forming. 


MANUFACTURE  AND  REPAIRS  OF  BOILERS         83 

Benefit  of  Preheating.  —  Another  very  satisfac- 
tory method  is  for  the  welder  to  heat  the  edges  of  the 
fissure  with  the  flame  until  they  become  plastic  and 
then  proceed  to  heat  the  adjoining  portions  of  the 
sheet.  The  result  is  that  the  metal  expands  toward 
the  edges  of  the  fissure  and  in  consequence,  the  plastic 
material  is  pressed  out.  The  sheet  is  then  allowed  to 
cool  down  completely  and  the  unfused  material  returns 
to  its  original  position,  leaving  a  wide  slot-shaped 
opening  in  place  of  the  crack. 

When  the  cooling  down  is  completed,  the  welder, 
by  inserting  the  filling  bar  into  the  middle  of  the  slot 
and  welding  a  small  central  portion,  is  then  able  to 
proceed  with  the  welding  from  either  end  of  the  fissure 
toward  the  centre.  In  this  case,  the  filling  bar,  which 
is  molten  in,  takes  the  place  of  the  chisel  in  the  pre- 
viously mentioned  process. 

To  prevent  the  crack  from  extending  further  a  hole 
should  be  drilled  at  each  end. 

Welding  in  Patches.  —  Cracks  in  boilers  usually 
occur  where  the  material  has  to  give  way  to  a  bending 
strain  in  a  certain  direction  and  if  it  can  be  avoided, 
the  welding  seam  should  not  be  placed  in  the  line  of 
such  strain.  It  is  more  advisable,  in  many  cases,  to 
cut  out  a  part  of  the  boiler  sheet  and  insert  a  new 
piece  instead  of  welding  up  a  fissure,  which  piece  should 
be  inserted  so  that  the  new  material  occupies  a  position 
in  the  line  of  strain. 

In  the  welding  in  of  a  patch,  it  is  also  of  advantage  to 
avoid  sharp  corners  in  the  piece  applied,  as  such  corners 
often  serve  as  a  starting  place  for  other  fissures.  The 
corners  should  therefore  be  rounded  off  and  those  of  the 
piece  applied  be  fitted  in  a  corresponding  manner. 

Method  of  Welding.  —  In  welding  in  such  a  piece 
it  is  necessary  to  start  the  welding  from  a  definite 


84  AUTOGENOUS  WELDING  AND  CUTTING 

point  usually  in  the  centre  of  one  side,  and  to  weld 
from  this  centre  to  either  end  of  the  straight  line. 
The  subsequent  welding  must  be  on  the  side  adjoining 
the  first  part  so  that  in  a  quadrangular  piece  the  two 
sides  forming  an  angle  are  welded  first. 

The  whole  piece  should  then  be  allowed  to  cool  and 
into  the  middle  of  the  angle  which  is  not  yet  welded, 
a  chisel  should  be  driven  and  the  material  forced  apart. 
Or,  a  filling  bar  should  be  welded  in  so  that  the  stretch- 
ing of  the  material,  in  the  welded  in  piece,  is  prevented 
during  the  latter  part  of  the  operation.  The  welding 
of  the  last  side  is  identical  with  the  method  of  welding 
a  fissure  described  above. 

Advantage  of  Dishing.  —  In  such  repairs,  the  piece 
of  sheet  which  is  to  be  inserted  may  also  be  somewhat 
"dished"  in  the  centre  and  if  a  piece  so  prepared  is 
welded  into  a  boiler  shell  it  will  be  found  that  the 
" dished"  part  becomes  straightened  upon  cooling,  in 
which  manner  tensions  are  prevented. 

Of  course,  such  welding  procedures  of  importance 
must  only  be  entrusted  to  workmen  with  experience 
on  similar  work  and  if  possible  only  to  those  who  have 
been  trained  for  repair  work  on  boilers  exclusively. 

Puddling  Process.  —  In  executing  this  kind  of  work, 
the  adjoining  portions  of  the  sheet  should  be  heated  to 
effect  a  transfer  of  heat  to  the  welding  place  from  the  ad- 
joining portions  instead  of  allowing  a  loss  of  heat.  In 
boiler  repair  work  the  welder  can  also,  with  advantage, 
employ  the  previously  mentioned  " puddling"  process 
where  the  metal  is  worked  by  means  of  small  hammers 
in  conjunction  with  the  application  of  the  welding  flame. 

A  very  common  operation  is  the  repair  of  furnaces, 
as  frequently  the  corrugations  of  the  furnace  tube,  with 
the  use  of  certain  water,  have  corrosions  formed  of 
sufficient  depth  eventually  to  render  the  boiler  useless. 


MANUFACTURE  AND  REPAIRS  OF  BOILERS         85 

Repairing  Corroded  Tubes.  —  These  corrosions  are 
often  found  in  great  numbers  on  the  water  side  of  fire 
tubes  and  furnaces.  The  welder  during  such  work 
should  keep  the  fire  door  and  chimney  of  the  boiler 
closed  to  prevent  the  cooling  down  of  the  material  by 
an  occasional  air  current,  which  would  spoil  the  suc- 
cess of  the  welding. 

This  work  puts  great  physical  strains  upon  the  welders 
and  in  many  cases  these  operations  must  be  executed 
by  two  alternating  gangs  of  workmen,  the  working 
periods  often  not  exceeding  20  minutes.  It  is  of 
great  importance  that  such  work  be  completed  without 
interruption  as  otherwise  strains  occur,  and  other  con- 
sequences follow,  which  are  injurious  to  the  welding. 


CHAPTER  XI 
MANUFACTURE    OF    CYLINDRICAL    VESSELS 

IN  welding  the  horizontal  seams  in  cylindrical  sec- 
tions of  thin  sheets,  it  is  of  advantage  to  employ  a  rail- 
way rail  or  similar  device  in  the  top  of  which  a  slot  is 
cut  lengthwise  about  20  m/m  wide  by  5  m/m  deep  (about 
f  x  3/16  inches).  The  rolled  sheet  is  placed  upon  the 


FIG.  83.  —  Method  of  using  supporting  rail  in  welding  longitudi- 
nal seam  in  a  cylindrical  section  of  thin  sheets.  Also  diagrams 
showing  two  methods  of  flanging  the  sheets  for  welding. 

rail  in  such  a  manner  that  the  flanges  to  be  joined  lie  in 
the  middle  of  this  slot  while  the  sheet  itself  is  imposed 
upon  the  rail  top  at  either  side  (Fig.  83). 

During  the  welding  process,  the  major  part  of  the 
heat  supplied  to  the  sheet  is  thus  conducted  into  the 
top  of  the  rail  so  that  undesirable  stretchings  or  warp- 
ings  of  the  sheet  are  prevented.  In  such  welding  rails 


MANUFACTURE  OF  CYLINDRICAL  VESSELS         87 

there  is  also  special  apparatus  for  carrying  the  sheet 
along  during  the  operation. 

Welding  of  Horizontal  Seams.  —  In  the  welding 
of  cylindrical  sections  of  heavy  sheets,  it  is  necessary 
to  take  the  expansion  into  careful  consideration.  If 
two  sheets  are  to  be  welded  lengthwise,  local  stretch- 
ings of  the  material  adjacent  to  the  welding  seam  will 
occur  in  consequence  of  the  heat  conducted  from  the 
welding  flame.  This  expansion  disappears  again  when 
the  welded  mass  cools  down. 

If  the  sheets  are  convexly  inclined  to  each  other, 
there  will  be  two  components  of  force  acting  from 
either  side  towards  the  welding  place  as  a  result  of  the 
expansion  of  the  sheets.  The  material  at  the  welding 
place  is  thus  compressed  and  is  lacking  when  the  mass 
cools  down  and  shrinks. 

At  the  same  time  a  warping  of  the  sheet  edges  occurs 
in  front  of  the  welding  place,  and  so  it  may  easily 
happen  that  the  edges  are  pushed  one  above  the  other, 
in  front  of  the  welding  seam. 

In  such  a  condition  the  article  is  useless  and  un- 
serviceable, for  if  attempt  is  made 
to  bring  the  sheet  back  to  its  origi- 
nal position  by  inserting  a  pin  in 
front  of  the  welding  seam  the  re- 
sult will  be  that  the  entire  section 
will  become  distorted. 


This  phenomenon  can  be  easily  Fl?-  84r~  Diasram 

/ing   sheet   prepared   for 

reproduced  if  one  punches  a  hole  in  demonstration  of  ten- 
the  middle  of  a  sheet  and  severs  ™**  produced  during 

the  welding  operation. 

the  sheet  trom  the   hole  to   one 

edge.  By  heating  the  area  around  the  hole,  the  area  of 
the  cut  will  be  converted  from  a  rectangular  to  a  trian- 
gular shape  (Fig.  84). 

If  the  welding  proceeded  from  the  edge  to  the  hole, 


88 


AUTOGENOUS  WELDING  AND  CUTTING 


the  welding  at  the  sheet  edge  however  good,  would 
always  burst  open  as  the  welding  approached  the  mid- 
_  die  of  the  sheet  (Fig.  85).  For 
this  reason  it  is  necessary  to  keep 
open  that  portion  of  the  sheet 
which  is  opposed  to  the  place 
where  the  welding  begins. 

It  is,  therefore,  best  to  insert  a 

FIG.  86.-  Diagram  show-     drift      in  b      means   of   which   it   j 
ing  the  effect  of  expan- 

sion  in  a  sheet  under  the    always  possible  to  bring  the  sheets 


into  the  P^Per  relative  position. 

This  pin  has  to  be  moved  on  as 
the  welding  proceeds  and  is  finally  removed  only  when 
it  is  necessary  so  that  the  welding  may  be  finished 
(Fig.  86). 

Welding  of  Circumferential  Seams.  —  Similar  pre- 
cautions must  be  taken  in  the  welding  of  circumferen- 
tial seams,  as  it  is  beneficial  to  place  the  edges  of  the 


FIG.  86. —  Method  of  preserving  the  correct  alignment  of  the 
edges  of  sheets  during  the  welding  operation. 

sheets  at  a  distance  of  about  2  to  5  m/m  (.08  to  .2 
inches)  from  one  another  according  to  the  thickness  of 
the  material.  This  is  best  accomplished  by  securing 
the  sheets  with  clamps  so  placed  as  to  preserve  the 


MANUFACTURE  OF  CYLINDRICAL  VESSELS 


sheets  in  correct  posi- 
tion for  welding  pur- 
poses. 


correct   alignment  and   also  to  keep  them  the  proper 
distance  apart  (Figs.  87  and  88). 

In  this  position,  the  sheet  sections  should  be  tacked 
together  between  the  clamps  by 
melting  down  filling  material  every 
few  inches  in  order  to  give  the  mass 
a  firm  position.  When  this  has 
been  done,  the  seam  can  be  safely  FIG.  87  —  Use  of  clamps 

„  ,  .  for    holding    edges    of 

welded  without  fear  of  cracking  or 
warping,  for  the  material  of  the 
sheets  is  then  placed  at  a  constant 
distance  from  each  other  and  the  movement  of  one  can- 

not handicap  the  movement  of  the 

other. 
Device    for     Welding     Heavy 

Sheets.  —  Where  large  and  heavy 

sheet  sections  are  to  be  made,  it  is 

of  advantage  to  employ  a  stretching 

ring,  of  U  shaped  cross-section  and 

a  radius  some- 

what less  than 

that  of  the  in- 

ner area  of  the 

sheet     section 

(Fig.      89). 


FIG.  88. —  Diagram  show- 
ing use  of  jig  for  main- 
taining correct  alignment 
and  distance  during  the 
welding  of  vertical  cylin- 
drical sections. 


in<rrrm<at 

U%  mUSt  FIG.  89.  —  Mandrel  for 

be  Open  On  One  use  in  welding  circum- 

•  j             i  ferential  seams  in  cy- 

Side    and    pro-  lindrical  sections. 


vided  with  an 

arrangement  for  adjusting  it  when  properly  placed,  so  as 
to  secure  the  correct  position  of  the  edges  to  be  welded. 
The  recess  in  the  block  permits  the  seam  to  be  welded 
without  affecting  the  device. 

The  stretching  appliance  may  consist  of  two  screws 
with    left    and    right   threads    and    hexagonal    nuts   or 


90 


AUTOGENOUS  WELDING  AND  CUTTING 


turnbuckles  of  suitable  dimensions,  which  are  adjusted 
after  both  sheet  sections  have  been  drawn  up  on  the 
rings.  The  two  sides  of  the  U  iron  segments  thus  press 
against  the  inner  side  of  the  sheets  and  serve  to  place 
the  edges  in  the  right  position  toward  each  other. 
Such  a  stretching  ring  has  a  similar  action  as  the 
welding  rail  fitted  with  a  lengthwise  groove. 

Bevelling  of  the  Sheets.  —  As  mentioned  above, 
it  is  necessary  to  bevel  the  edge  of  the  sheets,  if  thor- 
ough welding  of  thick  sheets  is  to  be  accomplished. 
In  factories,  where  such  operations  are  regularly  per- 
formed, the  sheets  are  bevelled  previous  to  the  rolling 
of  the  sheet,  if  the  necessary  appliances  are  at  hand. 
This,  however,  cannot  always  be  done,  and  it  is  then 
advisable  to  bevel  the  sheets  with  an  electric  grinder. 

In  the  manufacture  of  large  cylindrical  vessels,  the 
individual  sections,  which  are  to  be  welded  together 
by  circumferential  seams,  are  commonly  rested  upon 
supports  in  which  spools  are  inserted  so  that  the  whole 
body  can  be  easily  rolled. 

The  welding  of  the  seam  is  executed  either  from  a 

scaffold  covering  the 
vessel  or  a  pit  is  pro- 
vided in  the  floor  of 
the  workshop  where- 
by the  workman  is 
enabled  to  be  seated 
during  the  operation 
and  to  turn  the  body 

FIG    90  —  Diagram  of  pit  equipped  with     round  upon  the   rollg 

rolls  for  welding  circumferential  seams. 

as  the   welding   pro- 
ceeds (Fig.  90). 

An  efficient  welder,  when  he  observes  the  existence 
of  oxide  films  in  the  welding  place,  should  either  destroy 
these  mechanically  by  the  filling  bar  or  lift  them  to 


MANUFACTURE  OF  CYLINDRICAL  VESSELS          91 

the  surface  of  the  molten  mass.     This  necessitates  very 
strict  watching  of  the  molten  mass  by  the  welder. 

If  heavy  sheets  are  to  be  welded  the  workman  must 
also  stir  the  molten  mass,  with  the  filling  bar,  after 
the  edges  of  the  sheets  are  well  molten  under  the  in- 
fluence of  the  welding  flame. 

Joining  Pieces  of  Different  Cross  Sections.  —  In 
industry,  it  is  frequently  neces- 
sary to  weld  together  two  sheets 
of  different  cross-section.  In 
such  cases  the  welder  should 
first  heat  up  the  heavier  piece  to 


its  melting  temperature,  allow-  f 

ing  the  other  piece  to  be  heated 

indirectly.     Then  he    should 

sweep  the  thinner  piece  with  the  FIG.  91.— Method  of  welding 

welding  flame,  until  the  melting      together  two  sheets  of  dif- 
ferent thickness, 
point  of  it  also  has  been  reached, 

and  thus  thoroughly  fuse  together  the  material  of  both 
pieces  (Fig.  91). 

In  this  manner  a  good  weld  can  be  secured,  but 
proper  care  should  be  used,  as  the  melting  of  the 
heavier  part  demands  a  greater  amount  of  heat  than 
the  lighter  part. 

A  very  common  operation  is  the  welding  of  an  angle 
iron  ring  for  an  upper  joint  or  cover  connection  on 
sheet  metal  vessels.  A  difficulty  encountered  is  that 
in  the  welding  process,  one  side  of  the  angle  iron 
stretches  more  than  the  other,  the  consequent  dis- 
tortion making  the  iron  arc-shaped  so  that  it  has  to 
be  forcibly  pressed  down  upon  the  edge  of  the  sheet 
(Fig.  92). 

Application  of  Joint  Rings.  —  It  is  apparent  that 
under  such  circumstances  great  tensions  remain  in 
the  welding  seam.  To  prevent  this,  it  is  necessary  to 


92 


AUTOGENOUS  WELDING  AND  CUTTING 


heat  the  upper  side  of  the  ring  also  by  the  welding 
flame  during  the  welding  operation,  so  that  an  equal 


FIG.  92. —  Warping  of  an  angle-ring  during  the 
welding-on  operation. 

stretching  of  the  material  is  obtained  in  both  sections. 
The  welding  must  be  accomplished  during  this  state 
of  equal  stretching  (Fig.  93). 


FIG.  93. —  Diagram  showing  the  relative  positions 
of  the  welding  burner  to  secure  the  simulta- 
neous heating  of  both  sections  of  an  angle-ring 
to  prevent  warping. 

In  welding  such  rings  upon  sheet  vessels,  allowance 
has  to  be  made  for  the  thickness  of  the  material  of 
the  ring  being  considerably  greater  than  that  of  the 
sheet.  For  this  reason  it  is  necessary  to  direct  the 
welding  flame  chiefly  upon  the  part  in  which  the  ma- 


MANUFACTURE  OF  CYLINDRICAL  VESSELS 


93 


terial  is  stronger,  as  it  is  only  after  the  surface  of 
the  heavier  material  reaches  a  molten  state  that  the 
fusing  of  it  with  the  sheet  material  can  be  effected. 

Manufacture  of  Closed  Cylindrical  Vessels.  —  In 
manufacturing  cylindrical  vessels  with  rounded  ends 
it  is  common  practice  where  this  part  is  not  exposed 
to  special  strains  to  weld  an  ordinary  raised  head  on 
the  end  of  the  cylindrical  shell.  Such  work  is  similar 
to  the  welding  together  of  two  cylindrical  sections, 
although  at  times  it  is  advantageous  to  flange  both 
the  cover  and  shell  sheets  previous  to  the  welding 
operation. 

Such  method  of  executing  the  work  however  is  per- 
missible only  if  the  vessel  is  not  subjected  to  extensive 
internal  strains. 

All  vessels  under  the  influence  of  an  internal  pres- 
sure have  the  tendency  to  assume  a  shape  approach- 
ing that  of  a  sphere.  The  pressure  tends  to  increase 
the  diameter  of  the  cylindrical  part  of  the  vessel  in 
the  centre  and  to  press  the  cover  out- 
wards. Therefore,  if  in  such  a  vessel 
the  welding  occurs  immediately  at  the 
end  of  the  cylindrical  section  the  weld- 
ing seam  is  subjected  to  unequal  strains. 
Under  the  influence  of  the  pressure  ex- 
erted inside  of  the  vessel  the  outer  edge 
of  the  welding  seam  suffers  an  unusual 
compression  strain,  while  the  inner  edge 
has  to  stand  considerable  pulling  strain 
(Fig.  94). 

Internal  Strains.  —  It  is  well  known 
in  the  design  and  construction  of  boilers  that  a  bending 
strain  must  be  neutralized  by  the  radial  turning  up  of 
the  sheet.  In  the  cover  and  in  the  cylindrical  section 
of  such  vessels,  the  internal  pressure  pulls  upon  the 


FIG.  94.  —  Convex 
head  welded  on 
cylinder  with  dot- 
ted lines  to  indi- 
cate the  change  of 
shape  under  the 
pressure  strain. 


94 


AUTOGENOUS  WELDING  AND  CUTTING 


whole  longitudinal  section  of  the  welding  seam.  For  this 
reason  the  edge  of  this  cover  must  be  extended  cylin- 
drically  so  as  to  place  the  welding  area  in  the  cy- 
lindrical portion  of  the  vessel  (Fig.  95). 

It  is  possible  also  to  replace  the  bending  strain  in  the 
welding  seam  with  a  pulling  strain  by  forcing  in  the 
upper  edge  of  the  cylinder  body  and  inserting  a  cover 


FIG.  95.  —  Method  of 
applying  cylinder 
head  so  that  the 
welding  seam  will  be 
exposed  to  tension. 


FIG.  96. —  Cylinder  end  with  di- 
ameter reduced  to  permit  head 
to  be  applied  so  as  to  obtain  a 
pulling  strain  in  the  welding 
seam. 


somewhat  smaller  than  the  inner  diameter  of  the 
cylinder.  The  end  of  the  cylindrical  section  is  slowly 
heated  by  the  welding  flame  and  drawn  in  so  as  to  di- 
minish the  inner  diameter  at  that  point.  When  this  has 
been  accomplished  the  cover  is  inserted  and  welded  to 
the  cylindrical  section  in  the  usual  manner  (Fig.  96). 

This    practice    is    particularly    common   in    the    ship 
building  industry. 

Application  of  Bottom.  —  The  usual  method  for 
applying  the  lower  head  in  cy- 
lindrical vessels  is  to  form  an 
arched  head,  with  the  outside  di- 

FIG.  97.  —  Raised  inserted    ameter  slightly  less  than  the  in- 
head  applied  to  a  cylinder    ner  diameter  of  the  cylinder,  and 
to    rivet    it    to    the    cylindrical 

body  so  that  the  raised  part  of  the  head  extends  up- 
wards (Fig.  97). 

This  method  is  so  much  in  use  that  it  is  generally 


MANUFACTURE  OF  CYLINDRICAL  VESSELS          95 

considered  to  be  the  one  technically  correct,  but,  the 
fact  is,  that  there  is  no  other  means  of  rivetting  as 
the  interior  of  the  vessel  is  no  longer  accessible. 

It  will  therefore  want  a  certain  reversal  of  practice 
before  such  method  of  construction  is  abandoned  in 
favor  of  the  autogenous  welding.  The  welding  method 
must  therefore,  for  a  time  at  least,  subordinate  itself 
to  the  existing  conceptions  of  construction. 

The  application  of  a  raised  bottom  by  welding  is 
accomplished  by  first  welding,  or  tacking,  two  places 
of  the  circumferential  seam  which  are  diametrically 
opposite  and  then,  diagonally  to  the  axis  of  these  places, 
to  tack  in  a  similar  manner  two  others.  This  tacking  is 
then  continued  at  spaces  of  about  200  m/m  (8  inches) 
until  the  entire  circumference  has  been  so  treated  and 
then  the  welding  of  the  entire  seam  can  be  executed. 

Annular  Welding.  —  The  necessity  of  this  tacking 
is  due  to  the  fact  that  in  autogenous  welding  the 
expansion  stress  of  the  material  is  greater  in  the  cylin- 
drical section  than  in  the  unpliable  bottom  sheet.  If 
this  annular  welding  were  undertaken  without  pre- 
vious tacking,  the  external  sheet  would  expand  as  the 
welding  proceeded  until  it  would  be  forced  away  from 
the  head  in  the  shape  of  an  arc  which  could  by  no 
means  be  readjusted. 

The  metal  in  the  welding  seam  would  have  become 
useless,  while,  in  the  welding  area,  tensions  would  re- 
main acting  in  the  opposite  direction;  all  of  which  is 
avoided  by  previous  tacking  of  the  seam. 

The  following  method  can  also  be  employed:  If 
a  heavy  ring  of  material,  possessing  great  heat  con- 
ductivity, is  placed  around  the  outer  sheet  immediately 
above  the  welding  seam,  much  of  the  heat  infused  into 
the  sheet  by  the  welding  flame  will  be  absorbed  by 
this  extra  material.  The  infused  heat  will  therefore 


96  AUTOGENOUS  WELDING  AND  CUTTING 

be   distributed  over  a  larger  volume  of  material  and 
excessive  stretching  will  be  prevented    (Fig.  98)..    The 
most  effective  material  for  such  a  ring 
is  copper,  although  iron  may,  at  times, 
be  sufficient  for  the  purpose. 

In  vessels  of  this  type  it  is  usual  to 
provide   the    lower    bottom    sheet    of 
greater  thickness  than  that  of  the  cy- 
FIG.  98.  —  Method  of  lindrical  portion  and  it  is  accepted  as 
using   heat-absorb-   a  standard  that  both  lower  and  upper 

ing  plate  to  reduce  ,         ,       ,     ,,          ,    ,       .,  •>     . .  ,,       ,,  .   , 
tensions  during  the  heads  shall  each  be  1|  times  the  thick- 
operation  of  weld-  ness  Of  the  cylindrical  sheet, 
ing  on  a  head.                  T  •    i_-fj_         *     r\             •  TTJ.I 

Liability    of    Corrosion.  —  If    the 

vessel  manufactured  by  this  method  stands  upright  dur- 
ing use,  the  welding  seam  will  be  situated  at  the  ex- 
treme lower  end  of  the  vessel.  As  some  allowance  must 
always  be  made  for  the  existence  of  surface  moisture,  it 
is  possible  "that  premature  corrosion  may  occur  in  the 
seam,  sufficient  to  damage  the  vessel.  The  following 
method  has  been  evolved  to  prevent  such  a  defect  and  at 
the  same  time  secure  increase  in  strength. 

The  method  consists  in  heating  the  two  lower  edges 
of  the  sheet  of  the  cylindrical  vessel  and  its  bottom  by 
the  welding  flame  after  the  bot- 
tom has  been  inserted.  The  ap- 
plication of  heat  permits  the 
closing  in  of  the  edges  of  the 
sheets  toward  the  centre,  in  FIG.  99.  —  Drawing  in  the 

,  i          !  f  jv  edges  of  a  raised  cylinder 

the  shape  of  an  arc,  and  when  head  for  the  purpose  of  in- 
the  proper  contour  has  been  se-  creasing  the  strength  of 
cured,  the  welding  can  be  pro- 
ceeded with  in  the  usual  manner.  In  this  way  the  edge 
of  the  outer  sheet  is  so  drawn  around  that  it  absorbs  a 
part  of  the  strain  caused  by  the  internal  pressure  of  the 
vessel  (Fig.  99). 


MANUFACTURE  OF  CYLINDRICAL  VESSELS 


97 


The  welding  seam  at  the  base  of  such  vessels  can 
be  removed  beyond  the  reach  of  corrosion,  due  to  the 
collection  of  moisture  around 
the  exterior,  by  welding  an 
angle  iron  ring  on  to  the  ves- 
sel below  the  welded  area 
(Fig.  100).  The  proper  way 
to  manufacture  such  vessels 
consists,  however,  in  insert- 
ing the  top,  as  well  as  the 
bottom,  in  such  a  manner  so 

that  either  welding  seam  is   FIG.  100.—  Angle-ring  welded  on 
placed  in  the  cylindrical  part 
and  this   method    has    been 


the    bottom 

vessel. 


of    a    cylindrical 


generally  accepted  in  such  industry. 

When  a  vessel  thus  manufactured 
is  to  be  used  in  a  vertical  position,  it 
is  advisable  to  weld  an  angle  iron  ring 
to  the  external  shell  of  the  lower  head 
to  serve  as  a  support  to  the  vessel 
(Fig.  101). 

If  it  is  desired  to  apply  either  head 
of  such  vessels  somewhat  inside  of 
the  cylindrical  portion,  the  diameter 
of  the  head,  which  has  to  be  an  ex- 
act fit,  should  be  made  slightly  larger 
than  the  diameter  of  the  shell.  The 
outer  sheet  should  then  be  heated 
externally  so  as  to  expand  and  per- 
mit the  head  to  be  easily  inserted. 

FIG.    101.  —  Support  .J  ... 

ring  applied  to  a  ver-  The   welding  should   be   done   while 
tical  cylindrical  ves-  the  external  surface  is  still   hot   as, 

sel. 

otherwise,  there  would  be  danger 
of  the  welding  seam  bursting  during  the  welding 
process. 


O 


98 


AUTOGENOUS  WELDING  AND  CUTTING 


Applying  an  Intermediate  Head.  —  It  sometimes 
becomes  necessary  to  weld  an  intermediate  head  into 
a  cylindrical  vessel  in  a  place  that  is  otherwise  inac- 
cessible. Except  in  the  case  where  particular  strength 
and  lightness  are  required,  a  flanged  head  can  be  placed 
within  the  cylinder  into  which  a  number  of  holes  have 


FIG.  102.  —  Inserting  an  inter- 
mediate head  in  a  cylinder 
by  means  of  hole-welding. 


FIG.  103.  —  Inserting  an 
intermediate  head  by 
cutting  the  cylinder 
into  two  sections. 


been  previously  drilled.  With  ordinary  care,  the  oper- 
ator can,  by  inserting  the  torch  through  the  holes, 
weld  the  inner  intermediate  head  to  the  surface  of  the 
external  cylinder  shell,  after  which,  the  holes  can  be 
welded  up  (Fig.  102). 

If  the  intermediate  head  has  to  be  fitted  absolutely 
tight  and  capable  of  resisting  heavy  pressure,  it  is 
advisable  to  cut  the  cylinder  into  two  sections  and  to 
then  place  the  head  in  position  between  them.  By 
bevelling  the  edges  of  the  sheets  of  both  sections  of 
the  shell,  the  sections  can  be  placed  in  the  proper  posi- 
tion and  the  welding  executed  in  the  usual  manner 
(Fig.  103). 


CHAPTER   XII 

MANUFACTURE    OF    RECTANGULAR    VESSELS    AND 
MISCELLANEOUS    ARTICLES 

IN  the  manufacture  of  cylindrical  or  dome  shaped 
sheet  vessels  the  expansion  of  the  material  can  be 
absorbed  without  extensive  deformation,  but  this  is 
not  the  case  where  rectangular  bodies  are  to  be  made. 

Avoidance  of  Excessive  Expansion.  —  The  proper 
welding  of  flat  sheets  makes  it  imperative  to  avoid 
excessive-  heating  of  the  material  during  the  welding 
process,  or  to  localize  such  heat  upon  those  places 
which  are  not  flat.  The  latter  effect  is  obtained  by 
providing  the  sheet  body  with  a  flange  at  the  joining 
place,  and  then  to  weld  upon  the  upper  edge  of  this 
flange. 

Position  of  Welding  Torch.  —  If  the  welding  is  to 
be  done  in  the  corner  of  a  rectangular  vessel,  it  will 
be  necessary  to  place  the  burner  as  much  sideways  as 
possible,  in  the  direction  in  which  the  welding  is  to 
take  place.  It  is  thus  possible  to  reduce  to  a  minimum 
the  amount  of  heat  conducted  into  the  adjoining  flat 
parts  of  the  vessel.  If  the  burner  were  kept  vertically 
upon  the  welding  seam,  the  flame  jet  would  be  parted 
at  the  edge  and  thereby  considerable  areas  would  be 
heated  and  stretched  so  as  to  render  warping  of  the 
sheet  unavoidable  after  the  cooling  down. 

Location  of  Seams.  —  If  such  a  sheet  is  at  an  angle 
from  the  other  sheet,  it  is  advisable  to  place  the  union 
in  the  straight  portion,  at  a  distance  of  about  10  m/m 

99 


100 


AUTOGENOUS  WELDING  AND  CUTTING 


FIG.  104.— 
Method  of 
welding  on 
the  cover 
of  a  rec- 
tangula  r 
sheet  ves- 
sel. 


(f  inches)  from  the  edge.  Also  to  keep  the  position 
of  the  burner,  during  the  welding  operation,  so  that 
the  jet  does  not  flatten  itself  upon  the  flat 
part,  but  plays  against  the  corner. 

The  position  of  the  burner  is  very  essential 
for  avoiding  a  warping  of  the  sheet.  In 
welding  on  a  cover,  or  head,  it  is  advisable 
to  cut  the  cover  larger  by  about  20  m/m 
(f  inches),  and  to  bend  a  flange  of  about  10 
m/m  (|  inches)  in  width,  as  this  permits  the 
welding  to  be  effected  with  the  welding  flame 
directed  towards  the  flat  part  of  the  cover. 
Manufacture  of  Safes.  —  In  many  industrial  branches, 
as,  for  instance,  the  manufacture  of  safes,  distortion  of 
the  sheets  is  not  permitted.  If,  in 
such  cases,  the  welding  seam  has  to 
be  placed  in  the  corner,  a  heavy  cop- 
per plate  of  sufficient  dimensions 
should  be  laid  upon  the  cover  which 
is  to  be  welded.  The  vertical  sheet 
should  also  be  covered  with  a  heavy 
copper  band  placed  below  the  weld- 
ing seam  (Fig.  104,  105). 

By  this  arrangement,  the  excess 
heat  during  the  welding  operation 
passes  from  the  seam  to  the  copper 
plates,  owing  to  the  great  heat  con- 
ductivity of  such  metal,  and  the 
stretching  or  warping  of  the  sheets 
is  avoided. 

Superheaters. —  Autogenous  weld- 
ing is  adapted  for  many  purposes  in 
the  manufacture  of  heating  appliances,  as  it  provides  an 
excellent  means  for  joining  the  various  parts,  after  they 
have  been  stamped,  or  cut,  out  of  sheet  metal,  where 


FIG.  105.  —  Application 
of  heat- absorbing 
plates  to  prevent  the 
warping  of  the  sheets 
of  a  rectangular  ves- 
sel during  the  welding 
operation. 


MANUFACTURE  OF  RECTANGULAR  VESSELS       101 


rivetting  would  be  unsatisfactory.  This  is  true  of  super- 
heating devices  where  the  liquid  or  gas  conducted  through 
them  is  divided  into  the  thinnest  possible  layers,  in  order 

that  the  higher  heat     ^__ 

otherwise  given  to 
the  metal  can  be 
transmitted  to  the 
liquid  or  gas,  so  that 
the  latter  may  be- 
c  o  m  e  superheated 
accordingly  (Fig. 
106). 

Radiators.  —  Ra- 
diators for  house 
heating  or  similar 


FIG.  106. —  Tube  sheet  of  superheater  with 
autogenously  welded  pipe  connections. 


apparatus  of  the 
most  varied  types, 
which  are  kept  at  a 
pre-determined  temperature  by  circulating  water  or 
steam,  are  also  manufactured  from  sheet  metal  by  this 
method  at  considerable  less  cost  than  by  methods  for- 
merly employed  (Figs.  107  and  108). 

In  fact,  the  stamping  out  of  pieces  of  sheet  metal, 
the  flanging  of  the  edges  of  the  plates  to  be  welded 
and  the  welding  of  them,  employs  numerous  designs 
of  machinery  and,  not  only  now  forms  an  important 
industry,  but  extensive  developments  may  with  reason 
be  expected  in  the  future. 

Automobile  and  Aeronautical  Motors.  —  A  strik- 
ing example  of  the  scope-  of  this  work  is  the  automobile 
motor  shown  in  the  accompanying  illustration  (Figs. 
109  and  110).  This  is  composed  of  two  steel  tubes, 
for  the  cylinders,  and  several  stamped  sheet  metal 
pieces  welded  together  to  form  the  water  jacket  and 
fittings. 


102 


AUTOGENOUS  WELDING  AND  CUTTING 


FIG.  107.  —  Portion  of  a  ra- 
diator showing  manner  in 
which  the  individual  sec- 
tions are  welded  together. 


FIG.  108. —  Radiator  construc- 
ted from  sheets  by  means  of 
autogenous  welding. 


FIG.  109  FIG.  110 

FIGS.  109-110. —  Two  views  of  a  motor  cylinder  made  of  stamped 
sheet  sections  autogenously  welded  together. 

Such  motor  cylinders  have  a  distinct  advantage  over 
those  with  cast  iron  bodies  in  that  they  possess  greater 
strength  with  considerably  less  weight  and  the  defects 
and  service  cracks  experienced  in  cast  iron  cylinders 
are  entirely  avoided.  Motors  with  any  number  of 
cylinders  can  be  manufactured  in  this  manner. 


MANUFACTURE  OF  RECTANGULAR  VESSELS       103 

The  stamping  and  welding  method  thus  renders 
possible  the  production  of  articles  of  the  most  varied 
types  and  in  each  case  it  is  a  matter  of  determining 
the  approximate  cost,  to  decide  upon  the  method  to 
be  employed. 

When  making  sheet  metal  vessels  it  is  often  necessary 
to  apply  fittings  for  pipe  or  similar  connections.  For- 
merly this  was  accomplished  by  rivetting  a  suitable 
casting,  or  forging,  on  to  the  body,  but  such  connec- 
tions have  many  technical  deficiencies. 

Application  of  Pipe  Fittings.  —  This  form  of  connec- 
tion has  been  replaced  by  the  welding  on  of  a  boss 
of  whatever  metal  is  required  for 
the  purpose.  In  the  production  of 
this  work,  an  experienced  welder  FlG.  m._Boss  welded 

Can    build    the    boSS    Of    SUCh    shape        on  a  sheet  vessel  for 

and  in  such  a  manner  that  subse-  pipe  co™ectio11- 
quent  surface  finishing  is  unnecessary  (Fig.  111).  By 
boring  a  hole  through  the  boss  and  the  body  sheet,  which 
are  then  fused  together,  and  cutting  the  necessary  thread, 
a  thoroughly  satisfactory  connection  is  secured  into  which 
the  requisite  pipes  can  be  applied. 

Manufacture  of  Double  Shell  Vessels.  —  For  many 
industrial  purposes  vessels  with  double  shells  are 
employed  as,  for  example,  those  which  are  heated 
by  steam  or  hot  water  introduced  into  the  interlying 
space  between  the  two  shells.  The  manufacture  of 
such  vessels  has  been  much  simplified  by  means  of 
autogenous  welding  (Figs.  112-113). 

The  upper  edge  of  the  inside  vessel  should  be  bent 
toward  the  outside  by  means  of  a  flanging  machine, 
or  by  the  hammering  process,  so  that  the  outside 
diameter  of  the  flange  is  equal  to  the  outside  diameter 
of  the  other  vessel.  The  flanged  portion  of  the  inner 
vessel  can  then  be  welded  to  the  edge  of  the  outer 


104 


AUTOGENOUS  WELDING  AND  CUTTING 


FIG.  112.— Double-shell 
vessel. 


FIG.  113.— Vessel  with 
double  bottom. 


vessel  and  undue  tensions  need  not  be  feared  in  this 
operation. 

Open  Sheet  Metal  Vessels.  —  In  the  manufacture 
of  open  semi-circular  sheet  vessels,  where  the  bottom 
and  the  sides  are  made  out  of  one  sheet,  considerable 
economy  can  be  effected  by  cutting  out  the  corner 
in  a  similar  manner  to  that  shown  herewith.  The 
sheet,  so  cut  out,  can  then  be  formed  so  that  the  edges 
of  the  end  plate  and  the  edges  of  the  sides  come 
directly  against  each  other  and  can  be  welded  in  the 
usual  manner  (Figs.  114-115). 


n 


FIG.  114  FIG.  115 

FIGS.  114-115.  —  Diagram  showing  method  of  developing 
the  corner  of  an  open  vessel  made  from  a  flat  sheet  by 
autogenous  welding. 

In  actual  practice,  considerable  difficulty  is  often 
experienced  in  the  manufacture  of  cooking  and  similar 
utensils,  resulting  from  the  application  of  the  spout. 


MANUFACTURE  OF  RECTANGULAR  VESSELS       105 

When  the  spout,  which  has  previously  been  made  from 
two  stamped  pieces,  is  welded  on,  the  sides  of  the  ves- 
sel expand  and  thus  cause  blisters  which  spoil  the  gen- 
eral appearance. 

Cooking  Utensils.  —  If  the  hole  cut  in  the  vessel,  at 
the  place  where  the  spout  is  f 

to    be   fastened,   is    of   smaller 
diameter  than  the  spout  to  be 
applied,    the    material    can    be 
drawn    out    so   that   the  outer 
edge  fits  exactly  with  the  con- 
necting edge  of  the  spout.     The 
welding  on   of    the    spout    can 
then  be  not  only  more  easily,  FlG.  n6._  Method  of  apply- 
but  more  neatly,  done,  as  the      ing  a  spout  to  a  tea  kettle 
place  of  welding  is  more  acces- 
sible and  the  production  of  mis-shapen  vessels  is  also 
avoided  (Fig.  116). 

Ornamental  Articles.  —  In  addition  to  kitchen  uten- 
sils, various  special  articles  are  manufactured  as,  for 
example,  handles  of  ornamental  vases  of  the  most 
variegated  kinds.  Shells  of  pressed  sheets  are  made 
for  the  handles  of  canes  and  umbrellas.  These  are 
later  brought  upon  the  market,  after  they  have  been 
enameled,  engraved  and  inlaid  with  gold,  silver  and 
mother  of  pearl. 

The  welding  method  is  also  used  for  the  manufacture 
of  latch  keys,  door  handles,  window  handles,  gas  stove 
appliances,  apparatus  for  heating  by  the  exchange  of 
counter  currents,  connections  for  tube  conduits,  pistons, 
pedals  for  bicycles  and  articles  of  similar  nature. 

By  means  of  autogenous  welding  the  manufacture  of 
many  articles  is  made  possible  from  standard  shapes 
and  sizes  of  commercial  iron  and  one  need  only  refer 
to  one  of  the  most  important  articles,  as  an  illustration. 


106  AUTOGENOUS  WELDING  AND  CUTTING 

Window  Frames.  —  Iron  frames,  for  windows  and 
doors,  are  used  in  very  great  quantities,  in  factory  build- 
ings. A  simple  frame  of  angle  iron,  such  as  is  generally 

used  for  these  windows  can  be 
made  by  taking  the  necessary 
length  of  iron  and  cutting  out 
a  portion  of  one  side,  at  each 
— ^  corner  to  be  made,  as  shown 

herewith  (Fig.  117). 
1  •— ==s=4         The  frame  is  heated  at  each 

FIG.  117.-  Method  of  cutting  lace  and  bent  to  &  ^    M          j 
away  an  angle  iron  in   the  ° 
manufacture  of    a    window  SO   that    the    Outer    portion    re- 
frame  by  autogenous  weld-  mains  composed  of  undamaged 

material.  The  places  of  con- 
tact, formed  by  the  bevel  so  cut  at  the  corners,  are  then 
welded  together  autogenously  and  also  any  individual 
window  braces  that  may  be  desired. 

If  there  is  sufficient  length  of  iron  for  the  entire 
frame,  all  of  the  cutting  away  for  corners  can  be  first 
accomplished  and  when  the  iron  has  been  properly 
bent  the  welding  can  be  conducted  without  interrup- 
tion. Such  work  is  also  adaptable  to  armored  con- 
crete, and  in  other  various  ways,  in  the  building  trades. 


CHAPTER  XIII 


MANUFACTURE  AND  INSTALLATION  OF  LARGE  PIPES 
AND   CONDUITS 

FOR  the  manufacture  of  large  and  heavy  pipes,  by 
autogenous  welding,  the  ruling  items  have  been  fully 
dealt  with  in  the  manufacture  of  cylindrical  bodies. 
This  field  of  application  is  very  extensive,  as  large 
capacity  pipes  are  often  required  for  the  most  varied 
purposes. 

A  simple  tee  connection  is  made  by  cutting  the  nec- 
essary hole  in  the  main  pipe  somewhat  larger  than  the 
diameter  of  the  pipe  which  is  to  be  applied. 

Application  of  Tee  Connections.  —  The  end  of  the 
branch  pipe,  which  has  been 
previously  flanged,  is  closely 
fitted  to  the  contour  of  the 
outer  surface  of  the  main  pipe 
and  then  they  are  welded  to- 
gether (Fig.  118). 

A  better  practice,  however, 
is  to  make  the  hole  in  the 
main  pipe  somewhat  smaller 
than  the  diameter  of  the 


FIG.  118.  —  One  method  of  ap- 
plying a  tee  connection  on  a 
large  pipe  by  welding. 


branch  and  then  turn  the  edges  of  the  sheet  outwards, 
so  that  the  pipe  welded  on  fits  straight  on  to  the  edges 
thus  turned  up  (Fig.  119). 

A   branch   made   in   this   manner   is   not   only   more 
neat  in  appearance,  but  is  also  of  considerably  greater 

107 


108 


AUTOGENOUS  WELDING  AND  CUTTING 


strength,  as  the  welding  seam  is  not  subjected  to  the 
internal  strains  as  in  the  other  method.  Further  for 
conducting  gases  and  liquids,  this  latter  practice  is 

to  be  preferred,  as  it 
prevents  the  formation 
of  eddies  in  the  sub- 
stances flowing  through 
the  pipes. 

Making  of  Large  El- 
bows.  —  An  elbow  for  a 

FIG.  119.  —  Another  method  of  welding  large    capacity    pipe     is 
a  tee  connection  on  a  large  pipe.   (This  j        i 

method  is  recommended  in  preference  made     bY     ^paring     a 

to  that  shown  in  the  preceding  illus-  number  of  pieces,  which 

are  longer  on  one  side 

than  the  other,  and  uniting  these  segments  by  welding 
the  circumferential  seams  so  that  shortest  lengths  lie  in 
a  horizontal  line  (Fig.  120). 


FIG.  120.  —  Large  pipe  elbows  made  from  several  sheet  segments  by 
autogenous  welding. 

Another  way  to  make  an  elbow  in  such  pipes  is  to 
take  the  piece  of  pipe  of  sufficient  length  for  the  bend 
and  support  it  between  two  parallel  blocks.  Then 
heat  the  material  on  one  side,  by  means  of  one  or  more 


LARGE  PIPES  AND  CONDUITS 


109 


welding    torches,    until    it    is    stretched    on    that    side 
through  greater  expansion. 

By  continuing  the  heating  the  material  continues  to 
stretch  on  the  heated  side  causing  this  side  to  bulge. 
At  the  proper  time,  the  parallel  support  of  the  pipe 
is  removed  and  a  contraction  of  the  pipe,  on  the  inner 
side  of  the  bend  occurs,  thus  forming  a  regular  pipe 
elbow.  This  method  is  much  employed,  with  great 
success,  in  the  pipe  making  industry. 

When  erecting  pipe  conduits  it  is  necessary  to  take 
care  that  the  connections  are  made  in  fairly  large  sec- 
tions and  this  is  attained  by  using  flanged  screw  con- 
nections, at  regular  intervals. 

Welding  on  of  Flanges.  —  The  fixing  of  such 
flanges  on  to  the  pipe  wall  is  either,  through  threads 
cut  into  the  piping  and  in  the  inner  surface  of  the 
flange,  or  by  the  rolling  in  process,  or  by  means  of 
welding. 

With  the  welding  method,  it  is  necessary,  to  recess 
the  inner  bore  of  the  flange  on  a  lathe  so  that  the 
flange  can  be  firmly  welded  on  to  the 
pipe  end.  Where  it  is  practical,  a 
collar  can  be  turned  in  the  walls  of 
the  pipe  immediately  behind  the 
flange  (Fig.  121). 

In    the    regular    manufacture    of 
flanged  pipe  by  means  of  the  weld- 
ing process,  it  is  customary  to  use  a 
flange  with  a  collar  of  the  same  di-    FlG> 
ameter  and  approximately  the  same 
thickness  as  the  walls  of  the  pipe. 
The  edges  of  this  collar  are  united  with  the  pipe  by 
means  of  autogenous  welding. 

Experiments  have  proved  that  the  welding  on  of  a 
flange,  if  properly  executed,  will  resist  greater  pressure 


121.  —  Pipe  and 
flange  bevelled  pre- 
paratory to  welding. 


110  AUTOGENOUS  WELDING  AND  CUTTING 

than  if  the  pipe  is  threaded,  or  rolled  in,  and  the  joint 
made  in  this  manner  is  absolutely  gas  and  water  tight. 

When  erecting  pipe  lines,  one  must  also  bear  in  mind, 
that  expansion  and  contraction  of  the  piping  will  occur 
according  to  the  changes  in  temperature  to  which  they 
are  subjected. 

Compensation  Couplings.  —  These  changes  are  over- 
come by  inserting  compensation  sleeves  in  the  conduit 
at  desirable  places.  Such  parts  not  only  increase  the 
cost  of  the  piping,  but  necessitate  also  considerable 
space,  which  is  not  always  available,  particularly  in  the 
case  of  large  capacity  conduits. 


FIG.  122. —  Expansion  coupling  welded  between  pipe  flanges. 

In  ship  building  for  instance,  the  space,  which 
exists  between  the  sheets  of  the  double  bottom,  is 
used  for  accommodating  such  pipings.  Having  regard 
for  the  large  number  of  conduits,  which  are  required 
in  this  case,  the  question  of  accommodating  the  com- 
pensation sections  causes  the  builder- serious  difficulties. 

These  connections  are  often  made  to  advantage  by 
means  of  autogenous  welding  by  making  the  bends 
out  of  several  segments,  in  a  similar  manner  to  the 
above  mentioned  pipe  elbows. 


LAKGE  PIPES  AND  CONDUITS  111 

Corrugated  Sections. — There  is  a  very  simple  means 
of  avoiding  these  compensation  couplings  altogether, 
i.e.,  by  inserting  into  the  conduit  at  intervals  short 
pieces  of  piping,  which  have  been  provided  with  cir- 
cumferential corrugations  on  a  rolling  mill  (Fig.  122). 

Such  sections  are  very  similar  to  the  Morrison  or 
Fox  furnaces  used  in  steam  boiler  construction  and  these 
corrugations  provide  sufficient  elasticity  to  accommo- 
date the  expansion  and  contraction  of  the  piping,  re- 
sulting from  the  changes  in  temperature. 

Bends  inserted  at  intervals  also  serve  to  nullify  the 
effects  of  the  changes  in  the  material  which,  in  con- 
junction with  the  corrugated  sections,  eliminate  the 
difficulties  resulting  from  temperature  variations. 


CHAPTER    XIV 

MANUFACTURE  AND  INSTALLATION  OF  GAS  AND 
WATER  PIPE 

THE  manufacture  of  gas  and  water  pipe  furnishes 
a  field  for  autogenous  welding,  which  has  now  assumed 
great  proportions.  This  includes  pipes  of  all  diameters 
up  to  4  inches. 

The  method  previously  employed,  in  such  manu- 
facture, consists  of  cutting  the  sheet  metal  of  the  re- 
quired length  and  width  and  heating  the  strips,  in  a 
special  furnace,  usually  a  gas  oven,  uniformly  to  the 
welding  temperature  of  the  material.  When  this  tem- 
perature has  been  reached  the  strips  are  drawn,  direct 
from  the  oven,  through  suitable  dies  in  a  tube  drawing 
machine,  which  form  the  strips  into  the  shape  of  a  tube. 

Previous  Method  of  Manufacture.  —  As  the  ma- 
terial is  cooled  down,  during  this  operation,  to  a  tem- 
perature below  the  welding  point,  it  is  necessary  to 
return  the  partly  formed  pipe  to  the  oven  for  re- 
heating and  then  repeat  the  drawing  process,  with  the 
exception  that  a  smaller  die  is  employed.  During  this 
operation,  the  edges  of  the  strips  are  forced  against 
each  other,  pressed  firmly  together  and  thus  thoroughly 
welded. 

This  method  of  manufacture  was  adopted  when 
"puddled"  iron  was  in  general  use  and,  in  order  to 
obtain  a  good  weld,  two,  and  even  three,  drawings 
were  necessary  to  secure  satisfactory  results;  a  smaller 
die  being  used  at  each  successive  operation.  In  this 
work,  ordinary  fire  welding  is  used  and  the  reliability  of 

112 


GAS  AND  WATER  PIPE  113 

» 
such  welding  is  dependent  upon  the  overlapping  edges 

reaching  the  proper  welding  temperature  throughout. 

Although  the  pipe  drawing  is  an  exceptionally  quick 
operation,  local  coolings  of  the  material  often  occur 
as  the  result  of  currents  of  air  in  the  room,  caused  by 
the  opening  of  a  door  or  window,  and  as  a  consequence 
the  welded  section  is  not  as  perfectly  homogenous  as 
is  desirable.  The  existence  of  poor  welds  is  often 
in  evidence  when  the  material  opens  during  the  process 
of  cutting  threads. 

Use  of  Mild  Steel.  —  With  the  introduction  of  mild 
steel  into  modern  manufacturing,  a  new  material  was 
available  which  was  gradually  adopted  for  the  manu- 
facture of  gas  and  water  pipe.  The  structure  of  mild 
steel  is,  however,  quite  different  from  that  of  pig  iron 
and  during  the  drawing  operation  considerable  difficulty 
was  experienced  with  the  material  breaking  off  at  the 
drawing  tongs,  or  fracturing  at  the  die. 

Adoption  of  Rolling  Method.  —  For  this  reason,  the 
tube  mills  gradually  abandoned  the  drawing  method, 
in  pipe  manufacture,  and  adopted  pipe  rolling  machines, 
whereby  the  pipe  was  formed  from  a  strip  of  sheet 
metal1,  by  being  passed  through  a  series  of  profile  rolls 
(Fig.  123).  The  rolls  used  in  these  machines  varied 
in  size  owing  to  the  expansion  of  the  material  in  them 
due  to  the  increase  in  temperature  while  in  operation. 

This  constant  expansion  and  contraction  eventually 
produced  breaks  in  the  grips  of  the  rolls,  which  had  a 
bad  influence  on  the  product  and  made  it  necessary 
to  adopt  water  cooling  so  that  the  rolls  could  be  kept 
at  an  even  temperature.  Other  difficulties,  however, 
were  introduced,  for  when  the  strips,  at  welding  heat, 
were  run  through  a  series  of  water  cooled  rolls,  the  tem- 
perature of  the  metal  was  so  reduced  that  the  welding 
was  not  entirely  satisfactory. 


114  AUTOGENOUS  WELDING  AND  CUTTING 

The  foregoing  serves  to  illustrate  the  reasons  for  the 
development  and  application  of  autogenous  welding  in 
the  manufacture  of  mild  steel  pipes  and  the  extensive 
adoption  of  such  method  by  tube  manufacturers. 


FIG.  123. —  Pipe  rolling  machine. 

Autogenous  Welding  Process.  —  In  this  method,  the 
strips  of  sheet  metal  are  first  run  through  a  rolling 
machine,  to  be  formed  as  a  tube,  the  two  edges  of  the 
strip  butting  together  in  place  of  overlapping.  They 
are  then  placed  in  a  special  welding  machine  equipped 
with  several  sets  of  rolls  properly  adjusted  so  that  the 
edges  of  the  strips  are  conducted  under  a  fixed  welding 
flame  and  thoroughly  fused  together.  The  union  of 
the  metal  for  the  proper  dimension  of  pipe  is  secured 
by  means  of  a  set  of  welding  rolls  situated  immediately 
behind  the  flame  (Fig.  124). 

Defects  to  be  Avoided.  —  In  the  rolling  of  such 
pipe,  it  is  evident  that  a  V  shaped  groove  must  be 
formed,  where  the  edges  of  the  strip  butt  together, 


GAS  AND  WATER  PIPE 


115 


as  a  result  of  the  varying  stresses  on  the  material  and 
if  the  edges  are  fused  into  this  groove,  a  flattening  of 
the  outer  diameter  will  exist  at  the  welding  point. 
This  lack  of  material  will  become  evident  when  the 
pipe  is  threaded,  especially  in  thick-walled  pipes,  and 
it  is  absolutely  impossible  to  fuse  in  supplementary 
material  in  this  process. 

To  avoid  this  difficulty,  in  the  ordinary  pipe  rolling 
machines,  the  edges  of  the  strips  are  pressed  off  at  an 
angle  according  to  the 
radius  of  the  pipe  to 
be  made.  In  this 
manner,  the  upset  ma- 
terial at  the  edges  of 
the  rolled  strips  is 
fused  during  the  weld- 
ing operation  and  con- 
tributes to  improving 
the  quality  of  the 
pipes. 

In  some  of  the  tube- 
welding  machines,  a 
side  pressure  is  ex- 
erted, during  the  weld- 
ing process,  by  a  pair 
of  rollers  forcing  the 

tube  together,  causing  FIG.  124. —  Pipe  welding  machine  equipped 
a  combination  of  the  with  mechanically  operated  rolls. 

processes  of  autogenous  and  fire  welding  within  the 
seam. 

Welding  Speed.  —  The  usual  pipe  welding  machines 
are  arranged  so  that  the  formed  pipe  enters  the  machine 
in  a  cold  state  and  the  subsequent  welding  is  executed 
at  a  speed  of  about  1  foot  per  minute,  although  many 
such  welding  machines  operate  at  considerably  higher 


116 


AUTOGENOUS  WELDING  AND  CUTTING 


speeds.  Tubes  for  bicycle  frames  are  rolled  at  a  speed 
of  80  feet  per  minute  and  over,  which  is  much  higher 
than  the  working  speed  of  the  welding  machines.  The 
equipment  of  a  tube  mill  as  regards  such  machines  must 
vary  according  to  the  nature  of  the  work. 

Preheating.  —  Pipe  welding  machines  are  now  in  use 

with  fittings  which 
permit  the  pipe 
material  to  be 
heated  to  a  tem- 
perature of  800°  C. 
to  1000°  C.  (1472° 
F.  to  1832°  F.)  im- 
mediately before  it 
comes  under  the 
welding  flame.  By 
such  preheating, 
the  working  speed 
of  the  machine  is 
much  increased 
and  in  some  cases 


FIG.  125.  —  Pipe  welding  machine  equipped 
with  oil  preheater. 


double  the  capacity  has  been  secured  when  compared 
with  the  cold  method. 

At  present  there  are  two  different  methods  of  heat- 
ing, one  by  means  of  an  oil  flame  (Fig.  125)  and  the 
other  by  means  of  a  coke  fire  (Fig.  126). 

In  the  machines  using  the  coke  fire,  there  has  been 
considerable  difficulty  experienced,  due  to  the  ashes  from 
the  fire  lodging  between  the  edges  of  the  pipe  and  dam- 
aging the  weld.  This  can  be  eliminated  by  providing 
a  closed  oven  for  the  fire  with  a  collar  in  the  centre 
through  which  the  pipe  can  be  led,  so  there  will  be  no 
direct  heating  of  the  material  from  the  flame. 

Devices  for  Preheating.  —  A  French  engineer,  in 
an  endeavour  to  utilize  the  waste  heat  of  the  welding 


GAS  AND  WATER  PIPE 


117 


flame,  arranged  a  block  of  heavy  copper  immediately 
in  front  of  the  flame.  This  block  was  provided  with  a 
hole  for  the  passage  of  the  pipe  and  so  placed  that  the 
excess  portion  of  the  flame  heated  the  interior  of  the 
copper  block  and  this  heat  was  then  transmitted  to 
the  approaching  pipe. 


FIG.  126. —  Pipe  welding  machine  equipped  with  coke 
preheater. 


Such  a  preheating  device  is  practicable,  but  for  satis- 
factory results  it  would  be  necessary  to  prevent  the  loss 
of  heat  by  means  of  a  jacket  of  non-conducting  ma- 
terial on  the  exterior  of  the  copper  block.  If  the  excess 
heat  from  the  flame  was  insufficient,  supplementary 
heat  could  be  supplied  by  arranging  a  row  of  Bunsen 
burners  underneath  the  copper  block. 

In  welding  machines,  the  method  employed  for  pre- 
heating, whether  an  oil,  a  gas  or  a  coke  fire,  is  dependent 
entirely  upon  the  cost  of  the  fuel,  since  either  method 
is  entirely  satisfactory  with  proper  care. 

Guiding  Device.  —  In  the  existing  pipe  welding  ma- 
chines it  is  very  important  that  a  guiding  device  be 
fixed  in  the  cleft  of  the  pipe  which  is  not  yet  welded, 
so  that  the  place  to  be  welded  can  be  brought  properly 
under  the  welding  flame. 


118  AUTOGENOUS  WELDING  AND  CUTTING 

The  welding  flame  in  such  machines  also  requires 
attention  as  it  is  necessary  that  an  extraordinary  con- 
stancy of  pressure  and  uniformity  in  the  mixture  of  the 
gases  is  secured.  Care  should  be  taken  to  obtain  the 
maximum  uniformity  of  pressure  in  the  construction 
and  operation  of  the  acetylene  apparatus  adapted  for 
this  purpose. 

Reliability  of  Flame.  —  An  acetylene  apparatus, 
which  regulates  the  flow  of  gas  under  different  pres- 
sures, or  which  might  allow  blockages  in  the  outlet 
from  the  gasholder,  is  unsuitable  for  use  in  such 
welding. 

It  is  well  known  that  any  heating  of  the  material 
in  the  tip  of  the  welding  torch  when  in  use  will  cause 
a  change  in  the  mixing  proportion  of  the  acetylene  and 
the  oxygen. 

Cooling  of  Torch  Tip.  —  As  a  change  of  the  welding 
flame,  so  caused,  would  materially  damage  the  pipe 

manufactured,  it  is  essen- 
tial that  the  temperature 
of  the  burner  tip  be  kept 
at  an  even  degree  by 
means  of  a  water  cooling 
apparatus  (Fig.  127). 

FIG.  127.— Welding  burner  equipped     The    rollers    of    the    pipe 

with  water  cooling  device  for  pipe    welding  machine  may  also 

welding  machine. 

be  cooled  advantageously 
by  similar  water  circulation. 

Installation  of  Pipes  by  Welding.  —  In  addition  to 
the  benefits  resulting  from  the  application  of  autogenous 
welding  in  the  manufacture  of  pipe,  there  is  also  much 
economy  possible  by  the  introduction  of  this  method 
in  the  laying  of  such  pipes. 

In  the  laying  of  pipe  with  screw  couplings  as  was 
formerly  the  practice,  the  walls  of  the  pipe  are  de- 


GAS  AND  WATER  PIPE  119 

creased  by  one  half  of  their  thickness  through  the 
cutting  of  threads  for  connections  and  consequently 
the  resistance  capacity  is  correspondingly  decreased. 

The  strength  of  the  walls  of  the  pipe  must  therefore 
be  sufficient  for  the  pressure  as  well  as  for  tensile 
stress  and  the  depth  of  cut  of  the  thread  would  neces- 
sitate a  superfluous  thickness  of  material. 

By  the  methods  formerly  used  in  the  manufacture 
of  pipes  a  definite  thickness  of  material  had  to  be 
maintained  throughout  as  the  welding  could  not  be 
satisfactorily  accomplished  with  material  of  different 
thickness  in  the  same  section. 

Reduction  of  Material.  —  If  the  use  of  screw  pipe 
connections  is  abandoned  and  the  welding  of  pipe  ends 
is  adopted,  it  is  unnecessary  to  provide  thicker  pipe 
walls  for  such  installations  than  those  sufficient  to 
meet  the  subsequent  stresses. 

Autogenous  welding  offers  great  advantages,  there- 
fore, in  both  the  manufacture  and  installation  of  such 
pipe. 

It  is  very  essential,  however,  that  a  plumber  engaged 
in  such  work,  be  perfectly  familiar  with  the  autogenous 
welding  methods,  as  the  pipe  ends  and  the  joining  of 
side  branches  must  be  effected  upon  the  spot.  In  such 
installations  the  dripping  away  of  the  material,  on  the 
lower  part  of  the  pipe  shell,  must  be  avoided  as  the 
welding  must  necessarily  be  executed  at  the  end  of 
the  pipe. 

Education  of  Welders.  —  This  requires  the  use  of 
acetylene  apparatus  in  which  superheating  of  the  gases, 
during  the  generating  process,  is  excluded,  and  also 
requires  great  experience  and  practice  on  the  part  of 
the  workmen. 

In  the  instruction  workshop  of  the  autogenous  weld- 
ing of  metals  at  the  Royal  Technical  High  School  of 


120  AUTOGENOUS  WELDING  AND  CUTTING 

Cologne,  which  was  installed  by  and  is  now  under 
the  direction  of  the  author,  the  autogenous  installation 
of  tubes  has  been  made  a  special  subject  of  instruction, 
and  it  is  to  be  hoped  that  other  training  colleges  will 
follow  this  example. 


CHAPTER  XV 
CONSTRUCTION  OF  PIPE-SHAPED  APPARATUS 

THE  employment  of  autogenous  welding  in  the  man- 
ufacture of  pipes  has  developed  an  important  branch 
of  industry,  in  the  construction  of  cooling  apparatus, 
employing  the  system  of  heat  exchange  by  means  of 
counter  currents. 

Cooling  Apparatus.  —  Such  apparatus  consists,  usu- 
ally, of  an  undulating  shaped  pipe  capable  of  conduct- 
ing either  liquid  or  gas,  around 
which  a  similar  shaped  pipe  of 
larger  diameter  is  concentrically 
placed.  The  ends  of  the  outer 
pipe  are  closed  upon  and  welded 
to  the  walls  of  the  inner  pipes 


(Fig.  128) .    C  o  n  n  e  c  t  i  o  n  s  are   FlG>  128  _  Method  of  tack_ 
then  made  and  the  direction  of       ing  sheet  sections   before 
the  liquid   or  gas,   in  the  one       weldmg- 
pipe,  is  opposite  to  the  direction  of  the  second  fluid  in 
the  other  pipe. 

Ammonia  Machines.  —  Ammonia  cooling  machines, 
and  similar  apparatus  for  the  exchange  of  heat,  con- 
sist of  a  series  of  straight  tubes  arranged  parallel  and 
joined  at  alternate  ends  so  as  to  provide  a  continuous 
flow,  but  with  an  alternating  upward  and  downward 
movement.  The  straight  parts  of  such  tubes  are  en- 
cased in  larger  tubes,  the  ends  of  which  are  closed  in 
a  special  forming  machine  previous  to  their  application 
so  as  to  fit  the  outer  diameter  of  the  inner  tube  to 

121 


122 


AUTOGENOUS  WELDING  AND  CUTTING 


which  they  are  then  welded.  The  larger  tubes  are 
then  joined,  by  short  pipe  sections,  alternately  above 
and  below,  and  in  this  manner  a  very  efficient  counter 
current  heat  exchange  apparatus  is  produced  (Fig. 
129). 


FIG.  129.  —  Counter-current  cooling  apparatus  manufactured 
from  sheet  metal  by  autogenous  welding. 

The  industrial  possibilities  for  the  employment  of 
autogenous  welding  in  the  manufacture  and  assembling 
of  tubes  for  the  conduct  of  water  and  gas  are  very 
great.  Similarly,  extensive  use  is  also  made  in  the 
manufacture  of  thin  shelled  tubes  of  rather  small 
diameter  for  isolation  pipes  in  electrical  installations 
and  such  purposes. 

There  is  also  a  wide  field  in  the  manufacture  of  tubes 
for  the  construction  of  cycles,  flying  machines,  motor 
cars,  metal  furniture  and  other  purposes,  with  a  thick- 
ness of  material  varying  between  .5  m/m  and  1.5  m/m 


PIPE-SHAPED  APPARATUS 


123 


(1/64  and  1/16  inches)  and  numerous  large  factories  de- 
vote themselves  entirely  to  this  particular  industry. 

Bicycle  Tubing.  —  Such  tubes,  smoothened  out  by  a 
cold  drawing  process  after  having  been  completed,  are 
variously  employed  for  bicycle  manufacture.  In  these 
tubes,  the  material  is  often  required  to  stand  very  great 
strains  in  one  direction  and  for  this  reason,  tubes  have 
been  developed,  for  such  service,  which  possess  an  oval 
cross  section  in  place  of  a  circular  one.  This  is  ac- 
complished by  drawing  the  circular  tube  through  an 
oval  form  whereby  the  required  cross  section  is  secured. 

In  constructing  tubes  of  this  kind  which  are  used 
in  cycle  manufacture,  the  strain  upon  the  strength 
of  the  tube  is  usually  placed  in  its  lengthwise,  rather 
than  in  its  crosswise,  axis. 

A  certain  firm,  for  a  number  of  years,  produced  an 
oval  tube  that  was  particularly  su- 
perior to  its  rivals  owing  to  its 
greater  firmness,  and  during  this 
time,  the  manner  by  which  this 
greater  power  of  resistance  was  ob- 
tained remained  a  secret.  It  was 
only  on  the  occasion  of  a  lawsuit 
that  the  process,  used  by  this  firm, 
became  common  property  of  the 
engineering  world  at  large. 

Oval  Shaped  Tubing.  —  In  these 

tubes,  the  forming  of  the  oval  shape,    FlG  130  _  Oval-shaped 
from  the  circular  tube  was  arranged 
so  that  the  welding  seam  did  not 
lie  in  the  main  axis  of  the  tube,  as 
is  otherwise  common,  but  immediately  at  the  side  of  the 
axis  (Fig.  130). 

During  the  last  few  years,  the  construction  of  aerial 
craft  has  become  one  of  great  importance.  For  this 


bicycle  tubing  with 
welding  seam  outside 
the  line  of  strain. 


124  AUTOGENOUS  WELDING  AND  CUTTING 

purpose,  it  is  essential  to  employ  a  construction  tube 
of  as  little  weight,  but  as  great  a  power  of  resistance, 
as  possible. ' 

In  order  to  render  relatively  light,  and  thin  shelled 
tubes,  sufficiently  strong  for  the  great  strains,  in  the 
operation  of  aerial  machines,  the  author,  on  the  occa- 
sion of  the  International  Exhibition  of  Airships  at 
Frankfort  on  Main  in  1909,  proposed  several  such  con- 
struction tubes,  which  have  since  been  accepted  by 
industrial  concerns  (Fig.  131-132). 


FIG.  131. —  Two-section  FIG.  132. —  Three-section 

tubing  for  aerial  ma-  tubing   for   aerial   ma- 

chines, chines. 

Aeroplane  Frames.  —  If,  for  example,  two  triangu- 
larly shaped  tubes  are  placed  against  one  another  and 
the  places  where  they  touch  are  autogenously  welded 
together,  a  tube  is  obtained  of  light  weight  and  strong 
resistance.  Many  similar  tubes  can  be  made  of  the 
most  various  kinds,  according  to  the  purpose  for  which 
they  are  to  be  employed. 

In  welding  such  tubes  into  parts  of  machines,  it  is 
important  that  a  superheating  of  the  material  near  the 
welding  place  should  be  avoided. 

Joining  of  Tubes.  —  This  is  done  by  the  welder 
playing  the  flame  upon  the  union,  in  a  position  as 
horizontal  as  possible,  and  by  eliminating,  at  the  same 


PIPE-SHAPED  APPARATUS 


125 


time,  the  conduct  of  heat  from  the  welding  place  to  the 
adjoining  portions  of  the  material.  To  effect  the  latter 
purpose,  the  tubes,  for  a  short  distance  from  the  weld- 
ing seam,  should  be  surrounded  by  substances  which 
conduct  heat  readily,  as  for  example  copper,  so  that 
the  heat  is  absorbed  by  these  protecting  substances 
and  its  injurious  influence  upon  the  adjoining  material 
is  avoided. 

Where  it  is  of  advantage,  in  regard  to  the  strain 
which  it  is  later  called  upon  to  resist,  the 
part  may  be  hardened,  in  the  usual  man- 
ner, after  it  has  been  autogenously  welded. 
Miscellaneous  Apparatus.  —  In  making 
saddle  supports,  or  rims  of  bicycles,  from 
the  prepared  tube,  a  wedge  shaped  portion 
is  cut  out  so  as  to  leave  a  part  of  the 
original  tube  material  intact.  The  material 
is  then  beiit  round  and  the  touching  edges 
are  welded  (Figs.  133- 
134). 

In  the  construction  of  aerial  ma- 
chines, much  use  is  made  of  the 
autogenous  welding,  but  for  the 
want  of  space,  it  is  impossible  to 
go  further  into  this  most  interest- 
ing matter,  and  those  interested  are 
referred  to  the  respective  special 
literature  on  this  subject. 

A  process  analogous  to  the  manu- 
facture of  bicycles  is  the  making 
of  iron  furniture,  and  products  of 
the  most  various  kinds,  such  as 
bedsteads,  chairs,  etc.,  which  can  be  easily  manufactured 
by  means  of  autogenous  welding.  This  is  also  true  in 
the  manufacture  of  motor  cars. 


FIG.  133.—  Bi- 
cycle frame 
tubing  cut 
and  bent 
into  position 
ready  for 
welding. 


FIG.  134. —  Section  of  a 
bicycle  frame  auto- 
genously welded. 


126  AUTOGENOUS  WELDING  AND  CUTTING 

Tapered  Tubing.  —  In  pipe  manufacture,  it  is  often 
necessary  to  construct  a  pipe  of  such  shape  that  the 
ordinary  pipe  forming  and  pipe  rolling  machines  are 
unsuited,  particularly  tapered  pipes,  and  similar  shapes, 
which  are  formed,  by  the  inclined  roller  process,  and 
welded. 

Another  important  application  is  where  welded 
pipe  is  drawn  smaller  in  diameter,  at  regular  inter- 
vals, by  a  process  of  great  importance,  in  the  manu- 
facture of  ship  masts,  flag  poles,  lamp  posts,  fishing 
rods,  etc. 

Ship  Masts.  —  The  extent  to  which  such  process 
can  be  utilized  can  be  better  appreciated  when  it  is 
known  that  recently,  a  Westphalian  factory  success- 
fully undertook  the  manufacture  of  fishing  rods, 
whereby  a  pipe  of  25  m/m  (1  inch) 'diameter  was  re- 
duced, at  regular  intervals,  so  that  the  smallest  section 
had  a  diameter  of  only  5  m/m  (-5-  inch). 

Autogenous  welding,  capable  of  withstanding  such 
severe  stresses,  must  be  entirely  satisfactory. 


CHAPTER  XVI 
WELDING   OF  COPPER 

COPPER  is,  next  to  iron,  the  most  important  of 
metals  and  owing  to  its  dense  structure,  which  permits 
it  to  be  easily  polished,  together  with  greater  ductility, 
it  is  extensively  used  for  the  most  varied  industrial 
purposes.  It  has  a  specific  gravity  of  8.8  and  a  melting 
point  of  1084°  C.  (2084°  F.),  while  the  boiling  point 
is  1500°  C.  (2730°  F.). 

In  a  heated  condition,  copper  easily  combines  with 
atmospheric  oxygen,  forming  oxide  of  copper,  which 
compound  first  exists  only  on  the  surface,  but  later 
on,  becomes  absorbed  in  the  solid  material. 

The  normal  color  of  copper  is  a  light  salmon  red, 
but  when  oxidation  occurs,  the  color  changes  to  a  dark 
copper  and,  near  hard  soldered  places,  one  may  observe 
the  light  salmon  red  fractures  merging  into  the  dark 
brick  red  fracture,  if  the  material  is  broken  across  the 
joining  seam.  In  such  cases,  the  copper  is  said  to  be 
burned. 

Molten  Properties.  —  In  a  properly  adjusted  autog- 
enous welding  flame,  the  acetylene  receives  only  a 
sufficient  quantity  of  oxygen  to  convert  it  into  free 
oxide  of  carbon  and  free  hydrogen.  If,  on  the  other 
hand,  there  is  a  surplus  of  oxygen,  in  the  welding  flame, 
complete  combustion  of  the  gases  takes  place,  forming 
carbonic  acid  and  water.  When  this  occurs,  part  of  the 
flame,  which  contains  these  products  of  combustion,  has 
no  reducing  qualities  and  by  superheating  the  simultane- 

127 


128  AUTOGENOUS  WELDING  AND  CUTTING 

ously  formed  steam,  free  oxygen  is  liberated,  which 
combines  itself  with  the  copper. 

Molten  copper  has  a  great  capacity  to  absorb  gas 
and  particularly  hydrogen,  which  gases  are  again 
eliminated,  when  the  copper  solidifies.  They  rise 
in  bubbles  to  the  surface  and  then  burst,  shedding 
delicate  particles  of  copper  around  them.  This  phe- 
nomenon is  familiar  to  copper  founders. 

If  the  welding  place  of  the  copper  cools  and  the  solid- 
ifying of  the  surface  takes  place,  before  such  small  gas 
bubbles  have  been  liberated  from  the  molten  mass, 
these  bubbles  form  porous  places  in  the  copper  material. 

Copper  has  great  affinity  for  oxygen  at  temperatures 
considerably  below  the  melting  point,  losing  its  physical 
qualities  by  combining  with  it,  forming  oxide  of  copper. 

This  characteristic  of  copper  renders  it  necessary  to 
observe  strict  precaution,  in  the  autogenous  welding 
of  this  metal.  Also,  in  hard  soldering  of  copper,  this 
phenomenon  occurs  and  it  is  necessary  to  protect  the 
molten  metal  and  the  adjoining  parts  against  absorb- 
ing oxygen  out  of  the  atmosphere.  This  protection  is 
effected  by  the  application  of  a  welding  powder,  or 
flux,  which  has  a  melting  point  immediately  below, 
and  a  point  of  evaporation  somewhat  higher,  than  the 
melting  point  of  the  copper. 

Welding  Powders.  —  In  such  industry,  it  is  usual 
to  apply  mixtures  of  borates  and  silicates,  as  welding 
powders,  but  it  is  advisable,  in  welding  copper,  to  add 
a  substance  which  has  a  great  affinity  for  oxygen. 
Many  welding  powders  have  been  introduced  which 
contain  a  certain  percentage  of  compounds  of  phos- 
phorus and  compounds  of  borium.  Phosphorus  has 
the  particular  ability  to  reduce  oxides  of  copper  to 
metallic  copper,  while  at  the  same  time,  the  molten 
mass  becomes  as  light  a  liquid  as  water. 


WELDING  OF  COPPER  129 

In  copper  founding,  ingredients  of  phosphorus  are 
generally  used  in  the  melting,  but  a  high  phosphor  per- 
centage makes  the  copper  brittle.  The  quantity  of 
phosphorus  added  to  the  copper  must  not,  therefore, 
be  much  larger  than  is  absorbed  in  the  process  of  dis- 
oxidation  of  the  metal,  so  that  the  phosphorus  does 
not  remain  in  the  copper  substance  except  in  infinites- 
imal quantities,  which  are  harmless. 

Aluminium,  too,  has  valuable  dis-oxidizing  qualities, 
of  which  ample  use  is  made  in  the  manufacture  of 
steel  castings.  In  autogenous  welding  the  phosphorus 
is  usually  rendered  effective  by  the  employment  of 
copper  filling  bars,  which  have  a  small  percentage  of 
phosphorus,  but  not  more  than  0.05%.  These  filling 
bars  usually  contain  other  ingredients  in  small  quanti- 
ties, such  as  aluminium,  or  borium,  and  their  manu- 
facture requires  great  care. 

Small  ingredients  of  aluminium  make  the  homo- 
genous mixing  of  the  molten  mass  very  difficult,  as 
this  substance  has  only  about  one  fourth  of  the  gravity 
of  copper  and  equal  distribution,  over  the  whole  mass 
of  the  copper,  is  almost  impossible. 

Operation  of  Welding  Flame.  —  In  the  autogenous 
welding  of  copper,  it  is  important  that  the  welding 
flame  should  be  properly  adjusted.  Also,  if  the  inner 
cone  of  the  welding  flame  touches  the  molten  mass  of 
the  copper,  a  burning  of  the  copper  occurs,  as  will  also 
happen  to  the  filling  bars,  if  they  are  similarly  exposed. 

To  obtain  a  good  welding  of  copper,  it  is  necessary 
to  melt  down  the  joint  by  careful  operation  of  the 
torch  and  to  introduce  new  material,  from  a  suitable 
filling  bar  of  copper,  so  as  to  stir  the  molten  mass. 

If  the  filling  bar  has  a  certain  percentage  of  phos- 
phorus, the  latter  will  form  a  compound  of  phosphoric 
acid  with  the  oxides  of  copper,  which  are  being  dis- 


130  AUTOGENOUS  WELDING  AND  CUTTING 

oxidized.  This  acid  will  flow  along  the  surface  as  a 
thin  tough  film,  protecting  the  copper  from  the  oxygen 
of  the  atmosphere  and  consequently  superheating,  or 
oxidizing,  of  the  copper  cannot  take  place. 

In  this  case,  the  phosphoric  acid,  which  is  formed, 
replaces  the  welding  powder  which  would  otherwise 
be  required.  In  this  manner,  pure  welding  of  copper 
may  be  obtained  but  it  is  advisable,  and  particularly 
so  for  the  beginner,  to  employ  a  good  welding  flux  in 
addition. 

This  welding  powder  is  sprinkled  upon  the  surface 
of  the  copper  after  it  has  been  heated  and  melts  down 
into  a  film  shaped  coating.  It  is  advisable  to  cover 
the  mass  of  copper  to  be  welded,  on  either  side,  with 
welding  powder  in  this  manner,  for  in  copper  one  has 
to  deal  with  a  metal  which  has  a  melting  point  higher 
than  the  melting  point  of  its  oxides.  This  is  also  the 
case  in  alloys  of  copper. 

Avoiding  Burning  the  Metal.  —  The  experienced  work- 
man in  autogenous  welding  or  hard  soldering  is  able 
to  judge  from  the  glow  of  the  heated  spot  of  the  copper 
when  the  burning  of  the  metal  with  the  oxygen  of  the 
atmosphere  can  take  place,  as  this  state  of  heating  is 
characterized  by  a  dazzling  white  appearance.  If  it 
is  possible  to  effect  a  union  of  the  metal  before  this 
high  temperature  of  the  copper,  or  its  alloys,  is  reached, 
that  is,  if  a  temperature  is  secured,  which  is  immedi- 
ately below  the  melting  point  of  the  metal,  all  combus- 
tion of  the  metal  can  be  surely  avoided. 

There  have  been  methods  evolved,  by  numerous 
firms,  for  the  welding  of  copper  and  of  copper  alloys, 
which  are  founded  upon  such  process.  The  parts  of 
the  metal,  which  are  to  be  joined  together,  should 
first  be  cleaned  thoroughly,  at  the  place  of  welding, 
and  then  be  placed  one  upon  the  other  and  heated  by 


WELDING  OF  COPPER  131 

an  autogenous  welding  flame  to  a  temperature  slightly 
below  the  melting  point.  A  metallic  anvil,  or  rail, 
which  has  been  heated,  should  be  used  and,  upon  such 
support,  the  parts  to  be  joined  should  be  heated  and 
worked,  by  small  hammers,  so  that  a  kind  of  fire  weld- 
ing is  effected. 

Hammering  Method.  —  In  the  working  of  copper 
alloys,  such  as  brass,  bronze,  or  various  compositions, 
this  method,  particularly,  is  much  in  use.  For  this 
purpose,  small  hammers  with  heads  of  an  area  of 
8  m/m  (5/16  inch)  square  are  used  with  advantage. 
It  is  necessary  that  these  hammers  strike  that  part 
of  the  material  only,  which  has  been  heated  to  a  suit- 
able temperature,  under  the  influence  of  the  flame. 

Usually,  the  workman  takes  the  welding  torch  in 
one  hand,  with  the  small  hammer  in  the  other,  and 
effects  a  kind  of  puddling,  as  was  mentioned  above  in 
the  welding  of  mild  steel. 

The  employment  of  a  welding  powder  is  not  required 
in  this  case  but,  if  such  is  employed,  it  should  be  care- 
fully eliminated  from  the  joint  by  hammering.  In 
welding  brass,  or  brass  alloys,  the  parts  to  be  united 
may  also  be  washed  with  the  usual  soldering  water 
but  in  this  case,  the  surfaces  to  be  joined  must,  pre- 
viously, be  thoroughly  cleansed. 


CHAPTER  XVII 
WELDING  OF  ALUMINIUM 

THE  most  important  matter  to  consider,  in  the 
autogenous  welding  of  aluminium,  is  the  great  dif- 
ference between  the  melting  points  of  the  metal  and 
of  its  oxide.  Metallic  aluminium  melts  at  650°  C. 
(1200°  F.)  while  the  melting  point  of  the  oxide  of 
aluminium  is  upwards  of  3000°  C.  (5450°  F.). 

Another  important  item  is  the  great  affinity  of  alu- 
minium for  oxygen  and,  in  the  melting  of  the  metal,  it 
will  be  observed  that,  on  the  surface  of  the  single  small 
drops,  a  compound  is  formed  with  the  atmospheric 
oxygen  as  a  thin  and  tough  film. 

Influence  of  Oxide.  —  It  is  not  possible  to  destroy 
this  film  of  oxide  by  the  application  of  external  heat, 
although  this  heat  has  a  considerably  higher  tempera- 
ture than  the  melting  point  of  the  oxide.  In  the 
molten  metal,  its  melting  heat  remains  latent  and, 
notwithstanding  the  temperature  of  the  flame,  the 
film  of  oxide  is  cooled  down  to  the  melting  tempera- 
ture of  the  aluminium  metal  from  beneath. 

For  this  reason,  it  is  absolutely  necessary,  in  welding 
aluminium  that  the  film  of  oxide  be  destroyed,  which 
may  be  done  either  chemically  or  mechanically.  In 
the  autogenous  welding  process,  the  oxide  film  is  de- 
stroyed and  a  pure  metallic  combination  is  effected; 
in  which  respect,  it  differs  from  the  soldering  method. 
It  is  one  of  the  characteristics  of  the  soldering  method 
that  a  union  is  effected,  although  imperfect,  without  the 

132 


WELDING  OF  ALUMINIUM  133 

destruction  of  the  oxide,  so  that  a  film  still  exists  be- 
tween the  parts  that  have  been  united. 

Electrical  Properties.  —  This  is  of  great  practical 
importance,  for  aluminium  has  different  electrical 
properties  from  those  of  its  oxide.  Therefore,  in  each 
combination  of  masses  of  aluminium,  where  the  films 
of  oxide  intervene,  galvanic  chains  must  exist,  which 
eventually  lead  to  the  destruction  of  the  union. 

If  acid  is  present,  as,  for  example,  sulphuric  acid, 
which  is  found  diluted  in  the  atmosphere  of  industrial 
districts,  any  combination  that  has  taken  place  can- 
not be  satisfactory,  if  the  film  of  oxide  has  not  been 
destroyed. 

Mechanical  Destruction  of  Oxide.  —  The  destruction 
of  this  film  can  be  effected  by  mechanical  means.  In 
this  case,  the  surfaces  of  two  parts  of  metallic  alumin- 
ium are  put  one  upon  the  other  after  they  have  been 
cleaned  of  all  foreign  substance,  as  oil  or  grease.  The 
surfaces  are  then  heated  with  the  welding  flame  to  a 
temperature  of  about  400°  C.  (750°  F.)  and  are  then 
gently,  but  rapidly,  hammered.  In  this  manner,  the 
intervening  films  of  oxide  are  destroyed  and  the  metal 
is  welded  together. 

This  elimination  of  oxide  can  also  be  effected  by 
means  of  rolling.  This  process,  which  is  identical 
with  the  puddling  previously  mentioned,  is  employed 
on  a  great  scale,  for  the  most  various  purposes,  in 
Germany,  particularly  in  the  manufacture  of  sheet 
aluminium  vessels. 

Another  mechanical  method  consists  in  the  following 
process.  The  edges  of  the  aluminium  parts,  to  be 
united,  are  prepared  and  melted  in  the  usual  way, 
and  the  molten  material  is  then  stirred  with  the  filling 
bar.  In  this  manner,  the  films  of  oxide  are  destroyed 
and  it  is  thereby  possible  to  make  the  various  parts 


134  AUTOGENOUS  WELDING  AND  CUTTING 

flow  together  into  one  mass,  by  means  of  the  stirring, 
in  a  manner  similar  to  the  uniting  of  separated  drops 
of  mercury  poured  out  on  the  hand.  This  method  is 
impracticable,  in  the  case  of  rather  thin  sheet  metal, 
because  the  quantity  of  material  is  insufficient. 

Such  method  is  also  somewhat  unreliable;  as  there 
is  always  the  danger  that  a  small  detached  film  of  the 
oxide  is  molten  in,  causing  local  partitions  in  the  weld- 
ing seam. 

Chemical  Destruction  of  Oxide.  —  The  most  re- 
liable method  for  the  proper  uniting  of  parts  of  alumin- 
ium is  the  one  wherein  the  oxides  are  destroyed  by  a 
suitable  flux.  The  established  practices  of  autogenous 
welding  of  aluminium  are  founded  chiefly  on  the  use 
of  such  fluxes. 

This  flux  or  powder  consists  either  of  a  mixture  of 
alkali  chlorides  and  compounds  of  fluor  and  kalium 
with  chlorides  of  alkalies  or  the  latter  alone.  The 
composition  of  such  a  poWder  is  the  following:  — 

Kalium  Chloride                     (KC1.)  45% 

Lithium  Chloride                    (LiCl.)  15  % 

Natrium  Chloride                   (NaCl.)  30% 

Kalium  Fluoride                     (KF1.)  7% 

Double  Sulphide  of  Sodium  (NaHSO4)  3  % 

Welding  Powder.  —  The  melting  points  of  the  single 
constituents  of  such  a  mixture  vary  considerably  from 
each  other  and,  in  some  of  them,  the  melting  point  is 
above  that  of  the  aluminium  metal.  This  involves 
the  danger  that  single  parts  of  the  mixture  may  not  be 
melted  during  the  operation  and  thus  become  fixed 
within  the  molten  metal,  in  the  form  of  black  grains. 

This  imperfection  can  be  remedied  by  first  pulver- 
izing the  individual  constituents  of  the  flux  and  then 
proceeding  with  the  mixing  process  in  the  required 
percentages.  Such  a  powder  is  extraordinarily  hygro- 


WELDING  OF  ALUMINIUM  135 

scopic  and  absorbs  the  moistness,  which  is  always 
present  in  the  atmosphere,  thus  forming  a  pulpy  mass. 

For  this  reason,  such  powder  for  welding  aluminium 
must  never  be  left  standing  open  in  the  air  but  must 
be  kept  in  closed  bottles  and,  if  possible,  in  such  bottles 
as  are  fitted  with  ground  glass  stoppers.  It  is  also 
advisable  to  thoroughly  seal  the  bottle  with  a  thin 
coating  of  wax. 

Patent  Process.  —  In  Germany,  M.  U.  Schoop  has 
taken  out  two  patents  for  a  method  of  autogenous 
welding  of  aluminium.  The  principal  patent  protects 
a  process  for  the  welding  of  metal  with  the  use  of  a 
flux  consisting  of  a  mixture  of  alkali  chlorides.  The 
additional  patent  covers  the  addition  of  compounds  of 
fluor  to  such  mixtures.  These  two  patents  are  in 
possession  of  the  A.  G.  fur  Autogene  Aluminium 
Schweissung,  Zurich,  Switzerland. 

This  Company  manufactures  the  flux  in  the  form  of 
a  kind  of  paste,  which  is  put  upon  the  parts  of  the  alu- 
minium which  are  to  be  united  by  means  of  a  brush. 
The  welding  bar,  which  must  consist  of  pure  alumin- 
ium, is  also  plunged  into  this  paste. 

It  is  of  advantage,  in  the  employment  of  dry  powders, 
to  heat  the  filling  bar  so  that  the  welding  powder  will 
melt  and  flow  upon  the  bar  as  a  thin  film,  which  heating 
can  be  advantageously  done  by  the  welding  flame.  In 
the  welding  operation,  the  bar  must  be  kept  in  a  ver- 
tical position,  so  as  to  allow  the  film  of  the  flux  to 
flow  down  the  surface  of  the  bar. 

Care  must  be  taken  that  there  is  no  unnecessary  heat- 
ing of  the  powder  by  the  welding  flame,  or  touching 
of  it  by  the  inner  cone  of  the  flame,  because  some  of 
the  constituents  of  the  mixture  would  be  liable  to  evap- 
orate and  the  composition  of  the  rest  be  unfavourably 
influenced. 


136  AUTOGENOUS  WELDING  AND  CUTTING 

Sheet  Metal.  —  In  the  welding  of  sheet  metal,  the 
filling  bar  should  be  carried  in  the  direction  of  the 
welding,  so  the  filling  material  can  be  virtually  inserted 
in  the  trough. 

The  autogenous  welding  of  aluminium  requires  great 
skill  and  training  but,  properly  handled,  the  aluminium 
which  has  been  welded  is  nearly  equal  in  strength  to 
the  original  metal. 


CHAPTER  XVIII 
NICKEL  AND   OTHER  METALS 

NICKEL  is  extensively  employed  in  industry  both 
in  the  pure  state  and  in  alloys  with  other  metals.  On 
the  whole,  its  properties  are  very  similar  to  those  of 
iron. 

It  has  a  melting  point  of  1600°  C.  (2912°  F.)  and,  in 
a  molten  state,  has  the  property  of  absorbing  large 
quantities  of  gases,  particularly  oxygen,  which  gases 
remain  intact  after  the  mass  cools  down,  forming 
cavities. 

Another  property  of  great  importance,  in  the  autog- 
enous welding  of  nickel,  is  its  great  affinity  for  sul- 
phur, with  which  it  forms  many  compounds. 

It  is  frequently  stated  that  nickel  is  incapable  of  being 
welded  by  an  autogenous  welding  flame  but  this  is 
incorrect,  although  such  process  involves  considerable 
difficulties. 

Welding  Temperature.  —  Nickel,  like  iron  and  most 
other  metals  and  alloys,  is  entirely  weldable.  That 
is,  at  a  certain  heat  below  the  melting  temperature  it 
may  be  plastically  kneaded  by  means  of  mechanical 
force.  Further,  by  executing  the  union  at  a  tempera- 
ture below  the  melting  point,  the  injurious  absorption 
of  gases  by  the  metal  does  not  generally  occur. 

During  the  autogenous  welding  of  an  alloy  composed 
of  nickel  and  iron,  it  often  happens  that  the  nickel 
separates  from  its  alloying  component  and  a  fracture 
of  the  welding  seam  will  reveal  small  globules  of  pure 
nickel. 

137 


138  AUTOGENOUS  WELDING  AND  CUTTING 

Use  of  Heated  Anvil.  —  Due  to  its  great  capacity 
for  conducting  heat,  all  welding  of  nickel  must  be  done 
with  the  parts  resting  upon  an  anvil,  which  has  pre- 
viously been  heated  to  a  dark  red.  This  anvil  can  be 
heated  in  a  coal  fire  or  by  a  gas  flame. 

In  welding  two  plates,  in  the  manufacture  or  repair 
of  nickel  utensils,  it  is  necessary  that  the  faces  of  the 
two  parts  which  are  to  be  united,  must  be  thoroughly 
cleaned.  They  are  then  placed  upon  each  other,  heated 
to  a  temperature  just  below  the  melting  point,  with 
the  welding  flame,  and  hammered  together  with  small 
hammers.  With  proper  care,  the  two  parts  can  be 
thus  welded  to  a  homogenous  body. 

Hammering  Process.  —  When  two  slightly  heated 
nickel  pieces  are  thus  hammered  together  on  a  heated 
support  or  are  pressed  together  by  heated  rolls,  the 
direct  welding  which  takes  place  effects  a  pure  metallic 
combination  which  in  no  wise  differs  from  the  original 
metal  in  respect  to  structure  or  physical  properties. 

As  in  the  case  of  ordinary  iron,  the  existence  of  po- 
rous places  often  causes  much  trouble  in  rolling  mills 
and  frequently  rolled  nickel  plates  contain  porosities, 
which  are  not  discovered  until  they  are  further  machined. 
Formerly,  these  damaged  pieces  had  to  be  cut  out  and 
as  they  then  had  only  the  value  of  scrap,  extensive 
losses  in  labor  costs  were  often  occasioned. 

Repairing  Nickel.  —  In  repairing  such  places  by 
means  of  autogenous  welding,  the  porous  places  are  so 
worked  with  a  drill  as  to  clean  the  inner  walls  of  all 
foreign  matter.  After  sufficient  heating  of  the  piece 
in  the  vicinity  of  the  place  to  be  repaired,  a  pointed 
pure  nickel  wire  is  inserted  in  the  opening  and  at  the 
same  time  kept  constantly  heated  with  the  welding 
flame.  Such  work,  however,  must  be  done  with  the 
plate  resting  on  an  anvil  heated  to  a  dark  red, 


NICKEL  AND  OTHER  METALS  139 

In  the  manufacture  of  nickel  tubes  or  similar  ap- 
paratus, the  same  general  principles  must  be  employed 
and  appropriate  methods  can  be  developed  for  the  most 
varied  kinds  of  work. 

Rules  for  Welding  Nickel.  —  It  is  necessary  that 
the  following  rules  be  carefully  observed :  — 

1.  The   surfaces   to   be   heated   must   be    absolutely 
free  from  grease  and  oil  and  made  mechanically  clean 
by  scraping  or  similar  method. 

2.  The  work  must  be  done  while  the  material  rests 
on  an  iron  support  heated  to  from  700°  C.  to  800°  C. 
(1300°  to  1475°  F.). 

3.  The  hammering  must    be    performed    with    long 
handled  hammers  of  about  1  Ib.  weight  and  only  when 
the  nickel   plate   has  been  brought  to   a  bright   white 
heat  and  the  support  is  at  a  temperature  between  the 
figures  just  quoted. 

The  successful  welding  of  nickel  is  a  development  of 
great  importance  and  the  process  will  be  widely  applied 
in  the  future  as  soon  as  the  art  is  more  generally  under- 
stood. 

Welding  of  Silver.  —  Similar  phenomena  appear 
in  the  autogenous  welding  of  silver  as  in  the  welding 
of  nickel,  and  here  also  it  is  advisable  to  employ  the 
hammering  process  which  has  repeatedly  been  men- 
tioned for  the  effective  joining  of  the  metal. 

Welding  of  Gold.  —  Matters  are,  however,  quite 
different  in  the  autogenous  welding  of  gold  and  ample 
use  is  made  of  this  autogenous  welding  process  in  the 
goldsmith  industry.  In  the  working  of  gold  the  pure 
melting  process  is  all  that  is  necessary  to  be  employed 
for  the  metal  to  join  smoothly. 

Welding  of  Lead.  —  The  soldering  of  lead,  which  has 
been  introduced  into  industry  nearly  100  years  ago,  is, 
on  the  whole,  nothing  else  than  autogenous  welding, 


140  AUTOGENOUS  WELDING  AND  CUTTING 

which  soldering  can  also  be  executed  to  advantage 
with  a  welding  flame. 

As  the  melting  point  of  the  lead  is  very  low  and  its 
capacity  for  conducting  heat  is  relatively  small,  the 
work  with  the  oxy-acetylene  flame,  therefore,  must  be 
very  quickly  done. 

The  welding  of  thin  lead  sheets  especially,  by  the 
oxy-acetylene  flame,  requires  extraordinary  skill  and 
practice,  but  with  the  proper  handling  of  the  burner 
such  welding,  as  well  as  that  of  lead  bodies,  is  eco- 
nomical and  technically  very  advantageous. 

Welding  Together  of  Different  Metals.  —  It  is 
often  required  in  industry  to  weld  together  things  which 
consist  of  different  metals  as,  for  instance,  iron  and 
copper  or  alloys  of  copper.  On  the  whole,  the  prin- 
ciples given  on  the  subject  of  copper  welding  must  be 
observed. 

The  combustion  of  the  copper  must  be  avoided  and 
as  its  capacity  to  conduct  heat  is  much  greater  than 
that  of  iron,  the  iron  part  must  be  melted  down  first 
in  such  work  and  then  the  copper  must  be  made  to 
flow  into  the  iron,  employing  a  copper  bar  as  filling 
material. 


CHAPTER    XIX 
CONCLUSION 

IN  the  foregoing  pages,  the  working  of  the  most 
important  metals  and  metal  alloys  has  been  discussed 
and  an  attentive  autogenous  welder  will  be  able,  from 
the  text,  to  form  for  himself  a  clear  idea  in  regard  to 
such  metals  as  have  not  been  dealt  with  here,  as  to 
how  he  must  act  in  each  particular  case,  in  operations 
of  these  kinds. 

The  whole  of  the  technique  of  autogenous  welding 
is  at  the  present  time  in  a  course  of  technical  refine- 
ment. New  working  methods  are  constantly  appearing 
and  the  field  of  application  for  the  process  is  being  rap- 
idly extended. 

In  the  most  various  industrial  establishments  defi- 
nite working  methods  have  been  formed  but  which  are 
now  treated  as  manufacturing  secrets,  and  it  is  in  the 
nature  of  technical  development  that  such  processes 
should  gradually  become  the  common  property  of  all 
students  of  the  art  of  welding. 

The  process  which  is  considered  to  be  the  most  im- 
portant one  and  which  apparently  is  destined  to  pro- 
duce a  revolution  in  many  industries,  is  the  puddling 
process,  which  has  been  repeatedly  mentioned  in  the 
foregoing  pages.  The  physical  characteristics  of  metals 
frequently  alter  very  considerably  when  the  metal 
is  converted  into  a  molten  state,  and  it  is  apparent 
that  where,  by  the  melting  of  the  metal,  such  alteration 
occurs,  there  are  valuable  technical  advantages  in 

141 


142  AUTOGENOUS  WELDING  AND  CUTTING 

effecting  a  homogenous  combination  below  the  melting 
temperature,  as  can  be  secured  by  the  puddling  of 
the  heated  metal  parts. 

This  puddling  process  is  the  basis  of  the  fire  welding 
which  has  been  in  use  from  time  immemorial  and, 
with  the  introduction  of  aluminium,  it  returned  for 
technical  purposes  in  the  Hearus  process.  With  the 
constant  increase  in  the  number  of  metal  alloys,  which 
are  becoming  available  for  technical  purposes,  it  will 
also  play  an  important  part  in  the  autogenous  welding 
of  such  alloys. 

In  the  opinion  of  the  writer,  the  general  introduction 
of  the  puddling  process  opens  further  industrial  pros- 
pects, as,  by  this  means,  many  metals  and  metal  alloys 
can  be  satisfactorily  combined,  which  were  formerly 
considered  as  thoroughly  incapable  of  being  welded. 
This  opinion  was  held  because  such  metals,  in  their 
molten  condition,  have  great  capacity  for  absorbing 
the  gases  which  are  the  products  of  combustion  of  an 
autogenous  welding  flame,  which  would  render  autog- 
enous welding  seams  porous  and  brittle. 

Therefore  the  attention  of  the  students  of  autogenous 
metal- working  is  specially  directed  to  this  process  and 
its  future  development  is  earnestly  recommended  to 
them. 


INDEX 


Absorption  of  gases  by  molten  metal,  3,  4,  *13,  14,  54,  127,  137. 
Acetylene,  basis  of  manufacture  of,  7. 
chemical  properties  of,  5. 
combination  of  oxygen  and,  5. 
dissolved,  19. 
overheated,  11,  13,  14,  54. 
piping  of,  31. 
polymeres  of,  6,  11. 
purification  of,  20,  21. 
welding  pressure  of,  31,  35. 
Acetylene  dissous,  bottles  for,  19. 

burners  for  using,  19,  35. 
general  properties  of,  19. 
preparation  of,  19. 
shipment  of,  19. 
use  of,  19,  20. 
Acetylene  generators,  automatic,  17. 

carbide  to  water,  9,  10,  20. 
charging  and  cleaning  of,  10,  11,  13,  16,  17,  19. 
compressed  carbide,  12. 
dipping,  17. 
dust  carbide,  14. 
polymerisation  in,  11,  13. 
portable,  8. 
size  of  carbide  for,  8. 
stationary,  8,  12. 
temperature  limits  for,  10. 
water  requirements  of,  10,  20. 
water  to  carbide,  9,  16,  21. 
Acetylene  purifiers,  chemical,  20,  21. 

direction  of  gas  flow  in,  21. 
material  for,  21,  22. 
mechanical,  21. 

Advantage  of  using  welding  burners  larger  than  standard,  43. 
Aeronautical  motors,  manufacture  of,  101. 
Alloys,  welding,  of  copper,  131. 
of  nickel,  137. 
separation  of  components  of,  137. 


144  INDEX 

Aluminium,  autogenous  welding  of,  132. 
chemical  properties  of,  132. 
electrical  properties  of,  133. 
melting  point  of,  132. 
methods  of  destroying  oxide  of,  132. 
oxides  of,  132. 

patented  processes  for  welding,  135. 
physical  properties  of,  132. 
soldering  of,  138.. 
strength  of  welds  in,  133,  136. 
welding  powders  for,  134,  135. 
welding  of  sheet,  136. 
Annealing  metals  after  welding,  74. 
Annular  welding,  95. 
Autogenous  cutting  of  metals,  cost  of,  47. 

gas  consumption  of,  48. 
industrial  applications  of,  47. 
speed  of,  48,  49. 
theory  of,  44. 

Autogenous  welding,  different  processes  of,  2,  3,  4,  5. 
future  developments  of,  141. 
gas  consumption  in,  42. 
general  description  of,  1,  2,  50. 
industrial  applications  of,  1,  2. 
machines,  115. 
of  aluminium,  132. 
cast  iron,  58,  63. 
cast  steel,  59,  62. 
copper,  127. 
gold,  139. 
hard  steel,  60. 
iron,  61. 
lead,  139. 
mild  steel,  60,  62. 
nickel,  137. 

pieces  of  different  thickness,  91. 
pipe,  112,  114. 
sheet  iron,  68. 
silver,  139. 

two  different  metals,  140. 
wrought  iron,  60. 

puddling  process  of,  76,  131,  138,  139. 
Automobile  motor  manufactured  from  sheet  metal,  101. 

Back  firing  of  welding  burners,  31,  36,  39,  41. 
Beagid,  18. 


INDEX  145 

Bending  tests  of  autogenous  welds,  59. 
Benzine,  general  properties  of,  4,  5. 
Benzol  vapors,  general  properties  of,  4,  6. 

welding  uses  of,  5. 

Bevelling  of  metal  before  welding,  69,  90. 
Blaus  gas,  4. 

Blowholes  in  metal  after  welding,  54,  128,  137. 
Boilers,  steam,  causes  of  failures  in,  80. 
construction  of,  81. 

effect  of  temperature  variations  in,  80. 
manufacture  of,  81. 
repairs  to  sheets  in,  83,  84. 
repairs  to  tubes  in,  85. 

Boss  welded  on  vessel  for  pipe  connection,  103. 
Bottles,  capacity  of,  23. 

for  dissolved  acetylene,  19. 
hydrogen,  3. 
oxygen,  23. 
handling  of,  19,  29. 
repairs  to,  27,  28,  29. 
valves  and  fittings  for,  27,  28. 
weight  of,  26. 
Brass,  composition  of,  39. 

welding  of,  131. 
Burners,  adjustable,  36. 

back  firing  of,  31,  36,  39,  41. 
cleaning  of,  41. 

construction  of,  35,  39,  40,  44. 
cutting,  44. 
equal  pressure,  35. 
flame  adjustment  of,  37,  38. 
gas  consumption  of,  42,  48. 
injector,  31,  36. 
operation  of,  37,  38,  39,  42. 
selection  of,  36. 
use  of  large,  43. 
welding,  35,  39. 

Burning  of  metal  during  welding,  3,  13,  54,  72,  127,  130,  137. 
Bunsen  burners  for  preheating,  117. 

Calcium  carbide,  commercial  sizes  of,  7. 
compressed,  18. 
drums,  7,  8. 
dust,  14. 

general  properties  of,  7. 
heat  generated  by  gasification  of,  9. 


146  INDEX 

Calcium  carbide,  quality  of,  20. 

storage  of,  8. 

Carbide  to  water  generators,  9,  10,  20. 
Capacity  of  oxygen  bottles,  23. 
Carbon  in  molten  iron,  13,  50,  54,  62. 
Carbonising  flame,  38. 
Carbonization  of  metals,  38,  54. 
Care  of  burners,  41. 
Cast  iron,  expansion  of,  64,  65. 

filling  material  for  welds  in,  58. 
general  properties  of,  50,  57,  58,  64. 
melting  point  of,  64. 
repairs  of,  63,  65,  66. 
structure  of,  50,  57,  58. 
welding  of,  58,  59,  63. 
Cast  steel,  filling  material  for  welds  in,  59,  60. 

welding  of,  59,  62. 

Causes  of  burning  in  the  welding  seam,  54. 
Charging  acetylene  generators,  10,  11,  13,  16,  17,  19 
Chemical  process  for  producing  oxygen,  26. 
Chemical  properties  of  acetylene,  5. 

aluminium,  132. 
copper,  127. 
hydrogen,  2,  3. 
iron,  50. 
oxygen,  3,  5. 
nickel,  137. 
Chemical  purifiers,  design  of,  20. 

materials  used  in,  21. 
Circumferential  seams,  welding  of,  88. 
Cleaning  dust  filters,  22. 

generators,  10,  11,  13,  16,  17,  19. 
tips  of  burners,  41. 

Co-efficient  of  tension  in  cast  iron,  64. 
Combustible  gases,  2. 
Complex  castings,  repairs  to,  66. 
Composition  of  welding  fluxes,  58,  128,  134. 
Compressed  carbide  generators,  18. 
Conduits,    large,  compensation  couplings  for,  110. 
corrugated  sections  for,  111. 
elbows  for,  108. 

flanged  connections  applied  to,  109. 
installation  by  welding,  110. 
manufacture  of,  107. 
strength  of  welded,  109. 
tee  connections  welded  on,  107. 


INDEX  147 

Cooking  utensils,  manufacture  of,  105. 
Cooling  of  heated  welding  burners,  37,  40. 
Copper,  alloys  of,  131. 

autogenous  welding  of,  127. 
filling  material  for  welding  of,  129. 
hammering  method  in  welding  of,  131. 
influence  of  phosphorus  in,  129. 
melting  point  of,  127. 
oxides  of,  128. 

position  of  burner  in  welding,  129. 
properties  of,  127. 
soldering  of,  128. 
welding  powders  for,  128. 
Critical  temperature  of  air,  24. 

oxygen,  25. 
nitrogen,  25. 

Cutting  burners,  construction  of,  45. 
designs  of,  44. 
gas  consumption  of,  48. 
guiding  devices  for,  46. 
industrial  uses  of,  47. 
motor  driven,  46. 
operation  of,  45. 

Cylindrical  vessels,  circumferential  seams  welded  in,  88. 
closed,  93. 
construction  of,  86. 
corrosion  in,  96. 
heads  of,  94. 

horizontal  seams  welded  in,  27. 
intermediate  heads  applied  in,  98. 
internal  strains  in,  93. 
joint  rings  for,  92. 
large,  90. 
open,  91. 
supports  for,  97. 

Defective  welds,  54,  63,  71,  72,  128,  132,  137. 

Demonstrating  expansion  of  sheets  under  influence  of  welding  flame, 

87. 
Devices  for  use  in  autogenous  cutting,  46,  47. 

welding,  86,  88,  89,  90,  96,  100,  131, 

139. 

Diameter  of  hose  for  gas  welding,  31. 
Dipping  acetylene  generators,  17. 
Dissolved  acetylene,  bottles  for,  19. 

general  properties  of,  19. 


148  INDEX 

Dissolved  acetylene,  preparation  of,  19. 
use  of,  19,  20. 

welding  and  cutting  burners  for,  19,  35. 
Distinction  between  superheating  and  combustion  of  iron  in  welding, 

54. 

Double  shell  vessels,  manufacture  of,  103. 
Dust  carbide  generators,  14. 
Dust  filter  for  acetylene,  22. 

Education  of  welders,  119. 

Effect  of  excess  carbon  in  molten  iron,  54. 

Effect  of  temperature  variations  on  boiler  sheets,  81. 

Elbows  manufactured  from  sheet  segments,  108. 

by  unequal  heating  of  the  sheets,  109. 
Electrolytic  process  for  producing  oxygen,  25. 

general  description  of,  25. 

power  requirements  for,  26. 
Expansion  of  cast  iron  during  welding,  64,  65. 
Expansion  of  sheets  during  welding,  87. 

Experiments  in  autogenous  cutting  at  Birmingham,  England,  49. 
Explosions  in  acetylene  generators,  causes  of,  11. 

Failures  of  welds  in  aluminium,  132. 
cast  iron,  63. 
copper,  128. 
iron  and  steel,  54,  72. 

Filling  material  for  welds  in  aluminium,  135. 
cast  iron,  58. 
cast  steel,  59. 
copper,  129. 
hard  steel,  60. 
mild  steel,  60. 
nickel,  138. 
wrought  iron,  60,  70. 
Filter  for  acetylene,  22. 
Fittings  for  oxygen  bottles,  26,  27. 
Flame,  adjustment  of  burner,  37. 
carbonizing,  38. 
neutral  or  correct,  37. 
oxidizing,  37. 

Flanging  of  sheets  for  welding,  68,  69. 
Flexible  metal  hose  for  burners,  34. 
Fluid  for  testing  the  purity  of  oxygen,  24. 
Flux  for  welding  aluminium,  134,  135. 
cast  iron,  58. 
copper,  128. 


INDEX  149 

Flux  for  welding  steel,  61. 

wrought  iron,  61. 
Foaming  of  the  welding  seam,  13. 
Frames,  window,  made  by  welding,  106. 
Future  developments  in  autogenous  welding,  141,  142. 

Gases,  absorption  of,  by  molten  metals,  3,  4,  13,  14,  54,  127,  137. 
Gases,  combustible,  acetylene,  5. 
benzol,  4. 
blau,  4. 
hydrogen,  2. 
illuminating,  4. 
liquid,  4. 

Gas  consumption  of  burners,  42,  48. 
Gasifying  dust  carbide,  14. 
Gas  mains  in  welding  shop,  31. 
Generators,  acetylene,  automatic,  17. 

carbide  to  water,  9,  10,  20. 

charging  and  cleaning,  10,  11,  13,  16,  17,  19. 

compressed  carbide,  18. 

dipping,  17. 

dust  carbide,  14. 

polymerisation  in,  11,  13. 

portable,  8. 

size  of  carbide  for,  8. 

stationary,  8,  12. 

temperature  limits  for,  10: 

water  requirements  of,  10,  20. 

water  to  carbide,  9,  16,  21. 
Gold,  autogenous  welding  of,  139. 
Granulated  carbide,  7. 

Hammering  method  in  welding  of  aluminium,  133. 

copper,  131. 

nickel,  138. 

silver,  139. 

wrought  iron,  76,  84. 
Hard  steel,  filling  material  for  welds  in,  60. 

welding  of,  60. 

Heads  welded  in  cylindrical  vessels,  93,  94,  98. 
Heat  absorbing  plates,  70,  96,  100. 
Heat  generated  by  gasification  of  carbide,  9. 
Hole  welding,  98. 
Horse  power  required  for  producing  oxygen  with  electrolytic  process, 

26. 

Horse  power  required  for  producing  oxygen  with  liquid  air  process, 
25. 


150  INDEX 

Hose,  diameter  of,  31. 
fittings,  33. 
metal,  34. 
repairs,  34. 
rubber,  33. 

Hydrogen,  basis  of  manufacture,  2. 
bottles  for,  3. 

chemical  properties  of,  2,  3. 
commercial  uses  of,  3. 
difficulties  in  welding  with,  3,  52. 
shipment  of,  3. 
Hygroscopic  purifying  material,  21. 

Illuminating  gas,  difficulties  in  welding  with,  4. 
Impurities  in  acetylene,  20,  21. 
carbide,  20. 
iron,  52. 
oxygen,  23. 

Influence  of  phosphorus  in  copper,  128. 
Injector  burners,  31,  36. 

Installation  of  pipes  by  welding,  advantages  of,  118. 

in  ships,  110. 
methods  of,  109,  119. 
Instruction  schools  for  welders,  1 19. 
Intermediate  heads  applied  to  cylindrical  vessels,  98. 
Iron,  absorption  of  oxygen  by,  54. 
autogenous  welding  of,  52. 
carbon  percentages  in,  50. 
cast,  50,  57,  58,  63,  64. 
chemical  properties  of,  50. 
decarbonization  of,  52. 
impurities  in,  52. 
magnetic  properties  of,  74. 
malleable,  50. 
physical  properties  of,  52. 
Swedish,  59. 
white,  50,  52,  57,  63. 
wrought,  56,  60. 

Iron  oxide,  influence  of,  on  welds,  61. 
melting  point  of,  60. 
methods  for  destroying,  61. 

Joining  of  pieces  of  different  thickness,  91. 
Joint  rings,  application  of,  91. 

expansion  during  welding,  92. 

position  of  burner  during  welding,  92. 


INDEX  151 

Lead,  autogenous  welding  of,  139. 

soldering  of,  139. 

welding  of  thin  sheets  of,  140. 
Leaking  valves  on  oxygen  bottles,  27. 
Linen  cloth  for  dust  filter,  22. 
Liquid  air  process  for  producing  oxygen,  general  description  of,  24. 

power  requirements  for,  25. 
Low  pressure  acetylene,  35. 

Machines  for  cutting,  46. 
welding,  115. 
repaired  by  welding,  66. 
Magnetic  properties  of  iron,  74. 
Manufacture  of  acetylene,  7. 

automobile  motors,  101. 

bicycle  tubing,  123. 

boilers,  81. 

cookjng  utensils,  105. 

cooling  apparatus,  121. 

conduits,  107. 

cylindrical  vessels,  86. 

double  shell  vessels,  103. 

elbows  from  sheet  segments,  108. 

by  unequal  heating  of  sheets,  109. 

fishing  rods,  125. 

hydrogen,  2. 

liquid  gas,  4. 

metal  furniture,  125. 

open  sheet  metal  vessels,  104. 

ornamental  articles,  105. 

oxygen,  24,  25. 

pipe,  112. 

radiators,  101. 

rectangular  vessels,  99. 

safes,  100. 

ship  masts,  126. 

stamped  sheet  metal  articles,  101. 

superheaters,  100. 

window  frames,  106. 
Martinsite,  characteristics  of,  62. 

conditions  producing,  62. 
influence  on  the  welding  seam,  62. 
Mechanical  purifiers  for  acetylene,  21. 
Melting  point  of  aluminium,  132. 

aluminium  oxide,  132. 
copper,  127. 


152  INDEX 

Melting  point  of  iron,  60. 

iron  oxide,  60. 

nickel,  137. 

steel,  60. 
Method  of  developing  a  corner  in  the  manufacture  of  open  sheet 

metal  vessels,  104. 

Mild  steel,  autogenous  welding  of,  60. 

Miscellaneous  articles  manufactured  by  autogenous  welding,  105. 
Mixture  of  gases  in  burners,  40. 

Naphthaline,  6. 

Nickel,  autogenous  welding  of,  137. 

chemical  properties  of,  137. 

hammering  process  in  welding,  138. 

melting  point  of,  137. 

physical  properties  of,  137. 

repairing  of,  138. 

rules  for  welding  of,  139. 

use  of  heated  anvil  in  welding  of,  138. 

welding  alloys  of,  137. 

welding  temperature  of,  137. 
Non-hygroscopic  purifying  material,  21. 
Nozzles  of  cutting  burners,  44. 
welding  burners,  37. 

Open  sheet  metal  vessels,  manufacture  of,  104. 
Ornamental  articles,  manufacture  of,  105. 
Overhead  welding,  78.  + 

Overheated  acetylene,  effects  of  using,  14,  54. 

evidence  of  generation,  11. 
Overlapping  of  sheets  during  welding,  87. 
Oxides  of  aluminium,  chemical  destruction  of,  134. 
general  properties  of,  132. 
mechanical  destruction  of,  133. 
melting  point  of,  132. 
of  copper,  general  properties  of,  127. 

methods  of  destroying,  128. 
iron:  general  properties  of,  61. 
melting  point  of,  60. 
Oxidizing  flame,  37. 
Oxygen,  bottles,  for  shipment,  26. 
handling  of,  29. 
impurities  in,  23. 
measuring  consumption  of,  23. 
methods  of  production,  24,  25,  26. 
pressure  for  welding,  27. 
testing,  24. 


INDEX  153 

Oxy-acetylene  cutting,  data  on,  48. 
speed  of,  48. 

Oxy-acetylene  flame,  chemical  properties  of,  5. 
Oxy-benzol  flame,  practical  uses  of,  4. 

temperature  of,  4. 
Oxy-blau  gas  flame,  difficulties  in  welding  with,  4. 

practical  uses  of,  4. 
Oxy graph,  46. 

Oxy-hydrogen  cutting,  data  on,  48. 
speed  of,  48. 
Oxy-hydrogen  flame,  chemical  properties  of,  2. 

difficulties  with  in  welding  with,  3. 
influence  of  excess  of  oxygen  in,  3. 
practical  uses  of,  3. 
temperature  of,  3. 
Oxy-hydrogen  welding  outfit,  3. 

Pantograph,  46. 

Pearlite,  characteristics  of,  56. 

method  of  determining  percentage  of,  56. 
Phosphorus  in  acetylene,  20. 
copper,  128. 

Phosphuretted  hydrogen,  20. 
Pipe  flanges,  methods  of  welding,  109. 

preparation  for  welding,  109. 
strength  of  welded,  109. 

Pipe  installation  by  autogenous  welding,  118,  119. 
Pipe  manufacture,  autogenous,  112,  114. 

defects  to  be  avoided  in,  114. 
earlier  methods  of,  112. 
materials  used  in,  112. 
welding  machines  for,  115. 

Pipe-shaped  apparatus,  ammonia  machines,  121. 
fishing  rods,  126. 
heat  exchange,  121. 
metal  furniture,  125. 
ship  masts,  126. 
tubing  for  bicycles,  etc.,  123. 
Pipe  welding  machines,  burners  for,  118. 
designs  of,  115. 
flame  adjustment  for,  118. 
guiding  devices  for,  117. 
preheating  apparatus  for,  116. 
speed  of,  115. 

Piping  in  the  welding  shop,  31. 
Pit  equipped  for  welding  large  cylindrical  vessels,  90. 


154  INDEX 

Polymerisation,  phenomenon  of,  5,  11,  54. 

products  of,  6,  11. 
Portable  generators,  8,  16. 
Position  of  burner  during  welding,  70,  92. 
Powders,  welding,  for  aluminium,  134,  135. 
cast  iron,  64. 
copper,  128. 
iron  and  steel,  61. 
Preheating  of  boiler  sheets,  83. 
cast  iron,  64. 
methods  of,  64. 
of  pipe,  116. 
value  of,  64. 

Preparation  of  metal  for  welding,  59,  70. 
Pressure  reducing  valves,  26. 
Prevention  of  cracks  in  welding  of  cast  iron,  65. 
Puddling  process,  advantages  of,  77. 
for  aluminium,  133. 
boiler  repairs.  84. 
copper,  131. 
iron,  76. 
nickel,  138. 
silver,  139. 
future  of,  141. 
operation  of,  76. 
tools  for,  77,  139. 
Purification  of  acetylene,  20,  21. 
Purifiers  for  acetylene,  chemical,  20. 

materials  for,  21,  22. 
mechanical,  21,  22. 
Purifying  material,  hygroscopic,  21. 

non-hygroscopic,  21. 
Purity  of  oxygen,  23. 

Radiators,  manufacture  of,  101. 

Rail,  welding,  use  of,  86. 

Rectangular  vessels,  construction  of,  99. 

expansion  during  welding,  99. 
location  of  seams,  99. 
position  of  burner  for  welding,  99,  100. 
use  of  heat  absorbing  plates,  100. 
welding  cover  on,  100. 
Reducing  valves,  cleaning  of,  29. 

construction  of,  28. 
operation  of,  29. 
repairing  of,  30. 


INDEX  155 

Regulation  of  burners,  39. 

flame,  37. 

Reheating  of  metal  after  welding,  74. 
Repairs  by  autogenous  welding,  63,  138. 

Safes,  manufacture  of,  100. 

Schoop  process  of  welding  aluminium,  135. 

Sheet  iron,  autogenous  welding  of,  68. 

Silicon  in  cast  iron,  52,  58. 

Silver,  autogenous  welding  of,  139. 

hammering  process  in  welding  of,  139. 
•Stampings  of  sheet  metal,  69,  101. 
Stationary  acetylene  generators,  8,  12. 
Steel,  cutting  with  autogenous  flame,  44. 
general  properties  of,  50,  60. 
percentage  of  carbon  in,  50. 
cast,  composition  of,  59. 

filling  material  for,  59. 
welding  of,  60. 
hard,  filling  material  for,  60. 

welding  of,  60. 
mild,  composition  of,  50. 

filling  material  for,  60. 
melting  point  of,  60. 
welding  of,  60. 

Strength  of  welds  in  aluminium,  136. 
cast  iron,  59. 
pipe,  109. 
Styrolin,  6. 

Sulphuretted  hydrogen,  20. 
Sulphur  in  acetylene,  %). 
Superheaters,  manufacture  of,  100. 

Tacking  of  pieces  before  welding,  69,  121. 
Technique  of  autogenous  welding,  1,  141. 
Tee  connections  welded  on  large  conduits,  107. 
Temperature  limits  for  acetylene  generators,  10. 
Temperature  of  oxy-acetylene  flame,  4. 
benzol  flame,  4. 
hydrogen  flame,  3. 
required  for  welding  pipe,  116. 

Tensions  in  grey  iron  castings  and  their  influence  on  welding  opera- 
tions, 63. 
Testing  magnetism  during  welding,  76. 

oxygen,  apparatus  for,  24. 
Thick  sheets,  bevelling  of,  69. 


156  INDEX 

Thick  sheets,  failures  of  welds  in,  71. 
filling  material  for,  70. 
influence  of  oxides  in  welding  of,  72. 
position  of  the  burner  in  welding,  71. 
preheating  of,  73. 
preparation  for  welds  in,  71,  73. 
reheating  of,  74. 

Thin  sheets,  filling  material  for  welds  in,  71. 
flanging  for  welds  in,  68. 
position  of  the  burner  in  welding,  71. 
preparation  for  welds  in,  69. 
Tools  for  puddling  process,  77. 
Tubing,  welded,  for  aeroplanes,  124. 
automobiles,  122. 
bicycles,  123. 
furniture,  125. 
various  designs  of,  124. 

Union  by  welding  of  cast  and  wrought  iron,  62. 

iron  and  copper,  140. 
Use  of  two  welding  burners  simultaneously,  77. 

Value  of  re-heating  of  thick  sheets,  75. 
Valves  for  oxygen  bottles,  26. 
Vertical  welding,  78. 

Water  displacement  generators,  17. 

Water  requirements  of  acetylene  generators,  10,  20. 

Water  seal,  Fouche",  32. 

Herzfeld,  33. 

inspection  of,  33. 

with  pressure  chambers,  34. 

with  signal  whistle,  32. 
Water  superheated  to  high  temperature,  2. 
Water  to  carbide  generators,  9,  16,  21. 
Welding,  autogenous,  1. 
burners,  35. 

industrial  applications  of,  1,  2. 
machines,  115. 
of  aluminium,  132. 

cast  iron,  58,  63. 

cast  steel,  59. 

copper,  127. 

gold,  139. 

hard  steel,  60. 

iron,  61. 


INDEX  157 


Welding,  of  lead,  139. 

mild  steel,  60,  62. 
nickel,  137. 
pipe,  112,  114. 
sheet  iron,  68. 
silver,  139. 
wrought  iron,  60. 
pressure  of  acetylene,  31. 

oxygen,  27. 

puddling  process  of,  76,  84,  131,  138,  139. 
together  cast  steel  and  wrought  iron,  62. 

cast  iron  and  copper,  140. 
Welding  burners,  adjustable,  36. 

back  firing  of,  41. 
cleaning  of,  41. 
construction  of,  39. 
equal  pressure,  35. 
flame  adjustment  of,  37. 
gas  consumption  of,  42. 
injector,  36. 
operation  of,  71. 
selection  of,  43. 
use  of  large,  43. 

Welding  flame,  adjustment  of,  37. 
carbonizing,  38. 
chemical  properties  of,  5,  39. 
neutral,  37. 
oxidizing,  37. 

Welding  powder  for  aluminium,  134,  135. 
cast  iron,  58. 
copper,  128. 
iron  and  steel,  61. 
White  iron,  characteristics  of,  50. 
formation  of,  50,  63. 
Window  frames,  manufacture  of,  106. 
Working  pressure  of  acetylene,  31,  35. 

oxygen,  27. 
Wrought  iron,  autogenous  welding  of,  60. 

influence  of  oxides  in  welding,  61. 

melting  point  of,  60. 

use  of  flux  in  welding  of,  61. 


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MAR  IS   W» 


OflT  :I3  1938 


T       14   193o 


-IT 


17  1941 M 


NOV    4    1938 


MAY  12 1941 M 


MAR    IT  1939 


*&<- 


LD  21-95w-7,'37 


YB    I  I  165 


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